Util (JMRTD 0.7.29 API)

java.lang.Object
- org.jmrtd.Util

```
public final class Util
extends Object
```
Some static helper functions. Mostly dealing with low-level crypto.

Version:

$Revision: 1853 $

Author:

The JMRTD team ([email protected])

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`ENC_MODE` Mode for KDF.
`static int`	`MAC_MODE`
`static int`	`PACE_MODE`
`static DHParameters`	`RFC5114_1024_160` Deprecated. Existence of a "hidden SNFS" backdoor cannot be ruled out. see https://eprint.iacr.org/2016/961.pdf
`static DHParameters`	`RFC5114_2048_224` Deprecated. Existence of a "hidden SNFS" backdoor cannot be ruled out. see https://eprint.iacr.org/2016/961.pdf
`static DHParameters`	`RFC5114_2048_256` Deprecated. Existence of a "hidden SNFS" backdoor cannot be ruled out. see https://eprint.iacr.org/2016/961.pdf

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static ECPoint`	`add(ECPoint x, ECPoint y, ECParameterSpec params)` Adds two EC points.
`static PublicKey`	`addMissingParametersToPublicKey(AlgorithmParameterSpec params, PublicKey publicKey)` Attempts to add missing parameters to a public key.
`static byte[]`	`alignKeyDataToSize(byte[] keyData, int size)` Align the given key data.
`static BigInteger`	`computeAffineY(BigInteger affineX, ECParameterSpec params)` This just solves the curve equation for y.
`static byte[]`	`computeKeySeed(String cardAccessNumber, String digestAlg, boolean doTruncate)` Computes the key seed from a card access number (CAN) to derive secure messaging keys from.
`static byte[]`	`computeKeySeed(String documentNumber, String dateOfBirth, String dateOfExpiry, String digestAlg, boolean doTruncate)` Computes the static key seed, based on information from the MRZ.
`static SecretKey`	`deriveKey(byte[] keySeed, int mode)` Derives the ENC or MAC key for BAC from the keySeed.
`static SecretKey`	`deriveKey(byte[] keySeed, String cipherAlg, int keyLength, byte[] nonce, int mode)` Derives a shared key.
`static SecretKey`	`deriveKey(byte[] keySeed, String cipherAlg, int keyLength, byte[] nonce, int mode, byte paceKeyReference)` Derives a shared key.
`static SecretKey`	`deriveKey(byte[] keySeed, String cipherAlgName, int keyLength, int mode)` Derives the ENC or MAC key for BAC or PACE.
`static byte[]`	`ecPoint2OS(ECPoint point, int bitLength)` Encodes (using BSI encoding) an EC point (for use as public key value).
`static ECPoint`	`fromBouncyCastleECPoint(ECPoint point)` Convert a BC EC point to a JCA EC point.
`static Provider`	`getBouncyCastleProvider()` Returns the BC provider, if present.
`static byte[]`	`getBytes(String str)` Converts a string to bytes using UTF-8.
`static CertificateFactory`	`getCertificateFactory(String algorithm)` Returns a certificate factory object for the given certificate algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a certificate factory for the algorithm.
`static Cipher`	`getCipher(String algorithm)` Returns a cipher for the given encryption algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a cipher for the algorithm.
`static Cipher`	`getCipher(String algorithm, int mode, Key key)` Returns a cipher for the given encryption algorithm and key, possibly using the BC provider explicitly if the configured JCA providers cannot provide a cipher for the algorithm and key.
`static String`	`getCurveName(ECParameterSpec params)` Returns the curve name, if known, or `null`.
`static String`	`getDetailedPrivateKeyAlgorithm(PrivateKey privateKey)` Returns detailed algorithm information (including key length) about the given private key.
`static String`	`getDetailedPublicKeyAlgorithm(PublicKey publicKey)` Returns detailed information about the given public key (like RSA or) with some extra information (like 1024 bits).
`static KeyAgreement`	`getKeyAgreement(String algorithm)` Returns a key agreement object for the given algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a key agreement for the algorithm.
`static KeyPairGenerator`	`getKeyPairGenerator(String algorithm)` Returns a key pair generator for the given algorithm, possibly using the BC provider explicitly when the configured JCA providers cannot provide a generator for the algorithm.
`static Mac`	`getMac(String algorithm)` Returns a MAC for the given algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a MAC for the algorithm.
`static Mac`	`getMac(String algorithm, Key key)` Returns a MAC for the given algorithm and key, possibly using the BC provider explicitly when the configured JCA providers cannot provide a MAC for the algorithm and key.
`static MessageDigest`	`getMessageDigest(String algorithm)` Returns a message digest for the given algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a message digest for the algorithm.
`static BigInteger`	`getPrime(AlgorithmParameterSpec params)` Extracts the prime from the given DH or ECDH parameter specification which (hopefully) specifies a curve over a prime field.
`static PublicKey`	`getPublicKey(String algorithm, KeySpec keySpec)` Returns a public key for the given algorithm and key specification, possibly using the BC provider explicitly when the configured JCA providers cannot provide a public key for the algorithm and key specification.
`static byte[]`	`getRawECDSASignature(byte[] signedData, int keySize)` For ECDSA the EAC 1.11 specification requires the signature to be stripped down from any ASN.1 wrappers, as so.
`static Signature`	`getSignature(String algorithm)` Returns a signature for the given signature algorithm, possibly using the BC provider if the configured JCA providers cannot provide a signature.
`static byte[]`	`i2os(BigInteger val)` Converts a non-negative integer to an octet string.
`static byte[]`	`i2os(BigInteger val, int length)` Converts an integer to an octet string.
`static String`	`inferDigestAlgorithmFromCipherAlgorithmForKeyDerivation(String cipherAlg, int keyLength)` Infers a digest algorithm mnemonic from a signature algorithm mnemonic for use in key derivation.
`static String`	`inferDigestAlgorithmFromSignatureAlgorithm(String signatureAlgorithm)` Infers a digest algorithm mnemonic from a signature algorithm mnemonic.
`static String`	`inferKeyAgreementAlgorithm(PublicKey publicKey)` Attempts to infer a relevant key agreement algorithm (either `"DH"` or `"ECDH"`) given a public key.
`static String`	`inferProtocolIdentifier(PublicKey publicKey)` Infers an EAC object identifier for an EC or DH public key.
`static boolean`	`isPointOnCurve(ECPoint xy, ECParameterSpec ecParams)` Checks whether the given point is on the given curve.
`static boolean`	`isValid(ECPoint ecPoint, ECParameterSpec params)` Determines whether an EC point is valid with respect to the given EC parameters.
`static ECPoint`	`multiply(BigInteger s, ECPoint point, ECParameterSpec params)` Multiplies a scalar and an EC point.
`static ECPoint`	`normalize(ECPoint ecPoint, ECParameterSpec params)` Normalizes an EC point given the EC parameters.
`static ECPoint`	`os2ECPoint(byte[] encodedECPoint)` Decodes an EC point from a BSI encoded octet string.
`static BigInteger`	`os2fe(byte[] bytes, BigInteger p)` Converts an octet string to a field element via OS2FE as specified in BSI TR-03111.
`static BigInteger`	`os2i(byte[] bytes)` Converts an octet string to an integer.
`static BigInteger`	`os2i(byte[] bytes, int offset, int length)` Converts an octet string to an integer.
`static byte[]`	`pad(byte[] in, int blockSize)` Pads the input `in` according to ISO9797-1 padding method 2, using the given block size.
`static byte[]`	`pad(byte[] bytes, int offset, int length, int blockSize)` Pads the input `bytes` indicated by `offset` and `length` according to ISO9797-1 padding method 2, using the given block size in `blockSize`.
`static List<byte[]>`	`partition(int segmentSize, byte[] data)` Partitions a byte array into a number of segments of the given size, and a final segment if there is a remainder.
`static PublicKey`	`reconstructPublicKey(PublicKey publicKey)` Reconstructs the public key to use explicit domain params for EC public keys.
`static byte[]`	`recoverMessage(int digestLength, byte[] decryptedResponse)` Recovers the M1 part of the message sent back by the AA protocol (INTERNAL AUTHENTICATE command).
`static byte[]`	`stripLeadingZeroes(byte[] bytes)` Strips any leading zeroes from a byte-array and returns the resulting byte-array.
`static ECPoint`	`toBouncyCastleECPoint(ECPoint point, ECParameterSpec params)` Converts a JCA EC point to a BC EC point.
`static ECDomainParameters`	`toBouncyECDomainParameters(ECParameterSpec params)` Converts a JCA compliant EC parameter (domain) specification to a BC EC domain specification.
`static ECPrivateKeyParameters`	`toBouncyECPrivateKeyParameters(ECPrivateKey privateKey)` Converts the EC private key to a BC private key parameter specification.
`static ECPublicKeyParameters`	`toBouncyECPublicKeyParameters(ECPublicKey publicKey)` Converts the EC public key to a BC public key parameter specification.
`static ECNamedCurveSpec`	`toECNamedCurveSpec(ECNamedCurveParameterSpec namedParamSpec)` Translates internal BC named curve spec to BC provided JCA compliant named curve spec.
`static DHParameterSpec`	`toExplicitDHParameterSpec(DHParameters params)` Returns a Difie-Hellman parameter specification which includes the prime order of the subgroup generated by the generator if this information is available in the given (Bouncy Castle) parameters.
`static ECParameterSpec`	`toExplicitECParameterSpec(ECNamedCurveParameterSpec parameterSpec)` Translates (named) curve specification to JCA compliant explicit parameter specification.
`static ECParameterSpec`	`toExplicitECParameterSpec(ECParameterSpec params)` Translates (named) curve specification to JCA compliant explicit param specification.
`static byte[]`	`toOIDBytes(String oid)` Encodes an object identifier.
`static PublicKey`	`toPublicKey(SubjectPublicKeyInfo subjectPublicKeyInfo)` Extracts a public key from a BC subject public key info structure.
`static SubjectPublicKeyInfo`	`toSubjectPublicKeyInfo(PublicKey publicKey)` Convert the given JCA compliant public key to a BC subject public key info structure.
`static byte[]`	`unpad(byte[] bytes)` Unpads the input `bytes` according to ISO9797-1 padding method 2.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - ENC_MODE
```
public static final int ENC_MODE
```
    Mode for KDF.
    
    See Also:
    
    Constant Field Values
  - MAC_MODE
```
public static final int MAC_MODE
```
    See Also:
    
    Constant Field Values
  - PACE_MODE
```
public static final int PACE_MODE
```
    See Also:
    
    Constant Field Values
  - RFC5114_1024_160
```
@Deprecated
public static final DHParameters RFC5114_1024_160
```
    Deprecated. Existence of a "hidden SNFS" backdoor cannot be ruled out. see https://eprint.iacr.org/2016/961.pdf
  - RFC5114_2048_224
```
@Deprecated
public static final DHParameters RFC5114_2048_224
```
    Deprecated. Existence of a "hidden SNFS" backdoor cannot be ruled out. see https://eprint.iacr.org/2016/961.pdf
  - RFC5114_2048_256
```
@Deprecated
public static final DHParameters RFC5114_2048_256
```
    Deprecated. Existence of a "hidden SNFS" backdoor cannot be ruled out. see https://eprint.iacr.org/2016/961.pdf
- Method Detail
  - getBouncyCastleProvider
```
public static Provider getBouncyCastleProvider()
```
    Returns the BC provider, if present.
    
    Returns:
    
    the BC provider, the SC provider, or null
  - deriveKey
```
public static SecretKey deriveKey(byte[] keySeed,
                                  int mode)
                           throws GeneralSecurityException
```
    Derives the ENC or MAC key for BAC from the keySeed.
    
    Parameters:
    
    keySeed - the key seed.
    
    mode - either ENC_MODE or MAC_MODE
    
    Returns:
    
    the key
    
    Throws:
    
    GeneralSecurityException - on security error
  - deriveKey
```
public static SecretKey deriveKey(byte[] keySeed,
                                  String cipherAlgName,
                                  int keyLength,
                                  int mode)
                           throws GeneralSecurityException
```
    Derives the ENC or MAC key for BAC or PACE.
    
    Parameters:
    
    keySeed - the key seed.
    
    cipherAlgName - either AES or DESede
    
    keyLength - key length in bits
    
    mode - either ENC_MODE, MAC_MODE, or PACE_MODE
    
    Returns:
    
    the key.
    
    Throws:
    
    GeneralSecurityException - on security error
  - deriveKey
```
public static SecretKey deriveKey(byte[] keySeed,
                                  String cipherAlg,
                                  int keyLength,
                                  byte[] nonce,
                                  int mode)
                           throws GeneralSecurityException
```
    Derives a shared key.
    
    Parameters:
    
    keySeed - the shared secret, as octets
    
    cipherAlg - in Java mnemonic notation (for example "DESede", "AES")
    
    keyLength - length in bits
    
    nonce - optional nonce or null
    
    mode - the mode either ENC, MAC, or PACE mode
    
    Returns:
    
    the derived key
    
    Throws:
    
    GeneralSecurityException - if something went wrong
  - deriveKey
```
public static SecretKey deriveKey(byte[] keySeed,
                                  String cipherAlg,
                                  int keyLength,
                                  byte[] nonce,
                                  int mode,
                                  byte paceKeyReference)
                           throws GeneralSecurityException
```
    Derives a shared key.
    
    Parameters:
    
    keySeed - the shared secret, as octets
    
    cipherAlg - in Java mnemonic notation (for example "DESede", "AES")
    
    keyLength - length in bits
    
    nonce - optional nonce or null
    
    mode - the mode either ENC, MAC, or PACE mode
    
    paceKeyReference - Key Reference For Pace Protocol
    
    Returns:
    
    the derived key
    
    Throws:
    
    GeneralSecurityException - if something went wrong
  - computeKeySeed
```
public static byte[] computeKeySeed(String documentNumber,
                                    String dateOfBirth,
                                    String dateOfExpiry,
                                    String digestAlg,
                                    boolean doTruncate)
                             throws GeneralSecurityException
```
    Computes the static key seed, based on information from the MRZ.
    
    Parameters:
    
    documentNumber - a string containing the document number
    
    dateOfBirth - a string containing the date of birth (YYMMDD)
    
    dateOfExpiry - a string containing the date of expiry (YYMMDD)
    
    digestAlg - a Java mnemonic algorithm string to indicate the digest algorithm (typically SHA-1)
    
    doTruncate - whether to truncate the resulting output to 16 bytes
    
    Returns:
    
    a byte array of length 16 containing the key seed
    
    Throws:
    
    GeneralSecurityException - on security error
  - computeKeySeed
```
public static byte[] computeKeySeed(String cardAccessNumber,
                                    String digestAlg,
                                    boolean doTruncate)
                             throws GeneralSecurityException
```
    Computes the key seed from a card access number (CAN) to derive secure messaging keys from.
    
    Parameters:
    
    cardAccessNumber - the card access number
    
    digestAlg - the digest algorithm to use
    
    doTruncate - whether to truncate to 16 bytes or not
    
    Returns:
    
    the resulting key seed
    
    Throws:
    
    GeneralSecurityException - on error
  - pad
```
public static byte[] pad(byte[] in,
                         int blockSize)
```
    Pads the input in according to ISO9797-1 padding method 2, using the given block size.
    
    Parameters:
    
    in - input
    
    blockSize - the block size
    
    Returns:
    
    padded bytes
  - pad
```
public static byte[] pad(byte[] bytes,
                         int offset,
                         int length,
                         int blockSize)
```
    Pads the input bytes indicated by offset and length according to ISO9797-1 padding method 2, using the given block size in blockSize.
    
    Parameters:
    
    bytes - input
    
    offset - the offset
    
    length - the length
    
    blockSize - the block size
    
    Returns:
    
    padded bytes
  - unpad
```
public static byte[] unpad(byte[] bytes)
                    throws BadPaddingException
```
    Unpads the input bytes according to ISO9797-1 padding method 2.
    
    Parameters:
    
    bytes - the input
    
    Returns:
    
    the unpadded bytes
    
    Throws:
    
    BadPaddingException - on padding exception
  - recoverMessage
```
public static byte[] recoverMessage(int digestLength,
                                    byte[] decryptedResponse)
```
    Recovers the M1 part of the message sent back by the AA protocol (INTERNAL AUTHENTICATE command). The algorithm is described in ISO 9796-2:2002 9.3.
    
    Parameters:
    
    digestLength - should be 20
    
    decryptedResponse - response from card, already 'decrypted' (using the AA public key)
    
    Returns:
    
    the m1 part of the message
  - getRawECDSASignature
```
public static byte[] getRawECDSASignature(byte[] signedData,
                                          int keySize)
                                   throws IOException
```
    For ECDSA the EAC 1.11 specification requires the signature to be stripped down from any ASN.1 wrappers, as so.
    
    Parameters:
    
    signedData - signed data
    
    keySize - key size
    
    Returns:
    
    signature without wrappers
    
    Throws:
    
    IOException - on error
  - alignKeyDataToSize
```
public static byte[] alignKeyDataToSize(byte[] keyData,
                                        int size)
```
    Align the given key data.
    
    Parameters:
    
    keyData - the key data
    
    size - the new size
    
    Returns:
    
    a byte array with key data
  - i2os
```
public static byte[] i2os(BigInteger val,
                          int length)
```
    Converts an integer to an octet string. Based on BSI TR 03111 Section 3.1.2.
    
    Parameters:
    
    val - a non-negative integer
    
    length - the desired length of the octet string
    
    Returns:
    
    octet string
  - i2os
```
public static byte[] i2os(BigInteger val)
```
    Converts a non-negative integer to an octet string.
    
    Parameters:
    
    val - non-negative integer
    
    Returns:
    
    the octet string
  - os2i
```
public static BigInteger os2i(byte[] bytes)
```
    Converts an octet string to an integer. Based on BSI TR 03111 Section 3.1.2.
    
    Parameters:
    
    bytes - octet string
    
    Returns:
    
    a non-negative integer
  - os2i
```
public static BigInteger os2i(byte[] bytes,
                              int offset,
                              int length)
```
    Converts an octet string to an integer. Based on BSI TR 03111 Section 3.1.2.
    
    Parameters:
    
    bytes - a byte array containing the octet string
    
    offset - the offset of the octet string within the given byte array
    
    length - the length of the octet string
    
    Returns:
    
    a non-negative integer
  - os2fe
```
public static BigInteger os2fe(byte[] bytes,
                               BigInteger p)
```
    Converts an octet string to a field element via OS2FE as specified in BSI TR-03111.
    
    Parameters:
    
    bytes - octet string
    
    p - the modulus
    
    Returns:
    
    a non-negative integer modulo p
  - inferDigestAlgorithmFromSignatureAlgorithm
```
public static String inferDigestAlgorithmFromSignatureAlgorithm(String signatureAlgorithm)
```
    Infers a digest algorithm mnemonic from a signature algorithm mnemonic.
    
    Parameters:
    
    signatureAlgorithm - a signature algorithm
    
    Returns:
    
    a digest algorithm, or null if inference failed
  - inferDigestAlgorithmFromCipherAlgorithmForKeyDerivation
```
public static String inferDigestAlgorithmFromCipherAlgorithmForKeyDerivation(String cipherAlg,
                                                                             int keyLength)
```
    Infers a digest algorithm mnemonic from a signature algorithm mnemonic for use in key derivation.
    
    Parameters:
    
    cipherAlg - a cipher algorithm
    
    keyLength - the key length
    
    Returns:
    
    a (best effort approximation) digest algorithm that is typically used in conjunction with the given cipher algorithm and key length, or null if inference failed
  - toExplicitDHParameterSpec
```
public static DHParameterSpec toExplicitDHParameterSpec(DHParameters params)
```
    Returns a Difie-Hellman parameter specification which includes the prime order of the subgroup generated by the generator if this information is available in the given (Bouncy Castle) parameters.
    
    Parameters:
    
    params - parameters for Diffie-Hellman as a Bouncy Castle specific object.
    
    Returns:
    
    a JCE Diffie-Hellman parameter specification
  - getDetailedPublicKeyAlgorithm
```
public static String getDetailedPublicKeyAlgorithm(PublicKey publicKey)
```
    Returns detailed information about the given public key (like RSA or) with some extra information (like 1024 bits).
    
    Parameters:
    
    publicKey - a public key
    
    Returns:
    
    the algorithm
  - getDetailedPrivateKeyAlgorithm
```
public static String getDetailedPrivateKeyAlgorithm(PrivateKey privateKey)
```
    Returns detailed algorithm information (including key length) about the given private key.
    
    Parameters:
    
    privateKey - a private key
    
    Returns:
    
    detailed information about the given private key
  - getCurveName
```
public static String getCurveName(ECParameterSpec params)
```
    Returns the curve name, if known, or null.
    
    Parameters:
    
    params - an specification of the curve
    
    Returns:
    
    the curve name
  - toExplicitECParameterSpec
```
public static ECParameterSpec toExplicitECParameterSpec(ECNamedCurveParameterSpec parameterSpec)
```
    Translates (named) curve specification to JCA compliant explicit parameter specification.
    
    Parameters:
    
    parameterSpec - a BC named curve parameter specification
    
    Returns:
    
    a JCA compliant explicit parameter specification
  - toExplicitECParameterSpec
```
public static ECParameterSpec toExplicitECParameterSpec(ECParameterSpec params)
```
    Translates (named) curve specification to JCA compliant explicit param specification.
    
    Parameters:
    
    params - an EC parameter specification, possibly named
    
    Returns:
    
    another specification not name based
  - toECNamedCurveSpec
```
public static ECNamedCurveSpec toECNamedCurveSpec(ECNamedCurveParameterSpec namedParamSpec)
```
    Translates internal BC named curve spec to BC provided JCA compliant named curve spec.
    
    Parameters:
    
    namedParamSpec - a named EC parameter spec
    
    Returns:
    
    a JCA compliant named EC parameter spec
  - toSubjectPublicKeyInfo
```
public static SubjectPublicKeyInfo toSubjectPublicKeyInfo(PublicKey publicKey)
```
    Convert the given JCA compliant public key to a BC subject public key info structure.
    
    Parameters:
    
    publicKey - a public key
    
    Returns:
    
    a BC subject public key info structure
  - toPublicKey
```
public static PublicKey toPublicKey(SubjectPublicKeyInfo subjectPublicKeyInfo)
```
    Extracts a public key from a BC subject public key info structure.
    
    Parameters:
    
    subjectPublicKeyInfo - the BC subject public key info structure
    
    Returns:
    
    a public key or null
  - reconstructPublicKey
```
public static PublicKey reconstructPublicKey(PublicKey publicKey)
```
    Reconstructs the public key to use explicit domain params for EC public keys.
    
    Parameters:
    
    publicKey - the public key
    
    Returns:
    
    the same public key (if not EC or error), or a reconstructed one (if EC)
  - addMissingParametersToPublicKey
```
public static PublicKey addMissingParametersToPublicKey(AlgorithmParameterSpec params,
                                                        PublicKey publicKey)
```
    Attempts to add missing parameters to a public key. If the public key already has appropriate parameters, then this does nothing.
    
    Parameters:
    
    params - the parameter spec
    
    publicKey - the public key
    
    Returns:
    
    a public key with possibly added parameters
  - os2ECPoint
```
public static ECPoint os2ECPoint(byte[] encodedECPoint)
```
    Decodes an EC point from a BSI encoded octet string.
    
    Parameters:
    
    encodedECPoint - the encoded EC point
    
    Returns:
    
    the EC point
  - ecPoint2OS
```
public static byte[] ecPoint2OS(ECPoint point,
                                int bitLength)
```
    Encodes (using BSI encoding) an EC point (for use as public key value). Prefixes a 0x04 tag (without a length).
    
    Parameters:
    
    point - an EC Point
    
    bitLength - the length in bits to use for each coordinate (the field size)
    
    Returns:
    
    an octet string
  - inferProtocolIdentifier
```
public static String inferProtocolIdentifier(PublicKey publicKey)
```
    Infers an EAC object identifier for an EC or DH public key.
    
    Parameters:
    
    publicKey - a public key
    
    Returns:
    
    either ID_PK_ECDH or ID_PK_DH
  - add
```
public static ECPoint add(ECPoint x,
                          ECPoint y,
                          ECParameterSpec params)
```
    Adds two EC points.
    
    Parameters:
    
    x - an EC point
    
    y - another EC point
    
    params - the domain parameters
    
    Returns:
    
    the resulting EC point
  - multiply
```
public static ECPoint multiply(BigInteger s,
                               ECPoint point,
                               ECParameterSpec params)
```
    Multiplies a scalar and an EC point.
    
    Parameters:
    
    s - the scalar
    
    point - the EC point
    
    params - the domain parameters
    
    Returns:
    
    the resulting EC point
  - isPointOnCurve
```
public static boolean isPointOnCurve(ECPoint xy,
                                     ECParameterSpec ecParams)
```
    Checks whether the given point is on the given curve. This just checks the Weierstrass equation.
    
    Parameters:
    
    xy - a point
    
    ecParams - parameters specifying the curve
    
    Returns:
    
    a boolean indicating whether the point is on the curve
  - getBytes
```
public static byte[] getBytes(String str)
```
    Converts a string to bytes using UTF-8.
    
    Parameters:
    
    str - a string
    
    Returns:
    
    the bytes
  - getPrime
```
public static BigInteger getPrime(AlgorithmParameterSpec params)
```
    Extracts the prime from the given DH or ECDH parameter specification which (hopefully) specifies a curve over a prime field. (This will throw an IllegalArgumentException for non-prime fields.)
    
    Parameters:
    
    params - a parameter specification
    
    Returns:
    
    the prime
  - inferKeyAgreementAlgorithm
```
public static String inferKeyAgreementAlgorithm(PublicKey publicKey)
```
    Attempts to infer a relevant key agreement algorithm (either "DH" or "ECDH") given a public key.
    
    Parameters:
    
    publicKey - the public key
    
    Returns:
    
    either "DH" or "ECDH"
  - computeAffineY
```
public static BigInteger computeAffineY(BigInteger affineX,
                                        ECParameterSpec params)
```
    This just solves the curve equation for y.
    
    Parameters:
    
    affineX - the x coord of a point on the curve
    
    params - EC parameters for curve over Fp
    
    Returns:
    
    the corresponding y coord
  - toBouncyCastleECPoint
```
public static ECPoint toBouncyCastleECPoint(ECPoint point,
                                            ECParameterSpec params)
```
    Converts a JCA EC point to a BC EC point.
    
    Parameters:
    
    point - the JCA EC point
    
    params - the parameters to interpret the point
    
    Returns:
    
    the corresponding BC EC point
  - fromBouncyCastleECPoint
```
public static ECPoint fromBouncyCastleECPoint(ECPoint point)
```
    Convert a BC EC point to a JCA EC point.
    
    Parameters:
    
    point - the BC EC point
    
    Returns:
    
    the corresponding JCA EC point
  - isValid
```
public static boolean isValid(ECPoint ecPoint,
                              ECParameterSpec params)
```
    Determines whether an EC point is valid with respect to the given EC parameters.
    
    Parameters:
    
    ecPoint - an EC point
    
    params - the EC parameter specification
    
    Returns:
    
    a boolean indicating whether the EC point is valid with respect tot the given EC parameters
  - normalize
```
public static ECPoint normalize(ECPoint ecPoint,
                                ECParameterSpec params)
```
    Normalizes an EC point given the EC parameters.
    
    Parameters:
    
    ecPoint - the EC point
    
    params - the EC parameter specification
    
    Returns:
    
    the normalized EC point
  - toBouncyECPublicKeyParameters
```
public static ECPublicKeyParameters toBouncyECPublicKeyParameters(ECPublicKey publicKey)
```
    Converts the EC public key to a BC public key parameter specification.
    
    Parameters:
    
    publicKey - the EC public key
    
    Returns:
    
    a BC typed public key parameter specification
  - toBouncyECPrivateKeyParameters
```
public static ECPrivateKeyParameters toBouncyECPrivateKeyParameters(ECPrivateKey privateKey)
```
    Converts the EC private key to a BC private key parameter specification.
    
    Parameters:
    
    privateKey - the EC private key
    
    Returns:
    
    a BC typed private key parameter specification
  - toBouncyECDomainParameters
```
public static ECDomainParameters toBouncyECDomainParameters(ECParameterSpec params)
```
    Converts a JCA compliant EC parameter (domain) specification to a BC EC domain specification.
    
    Parameters:
    
    params - the EC parameter specification
    
    Returns:
    
    the corresponding BC typed EC domain parameter specification.
  - getCipher
```
public static Cipher getCipher(String algorithm)
                        throws GeneralSecurityException
```
    Returns a cipher for the given encryption algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a cipher for the algorithm.
    
    Parameters:
    
    algorithm - the encryption algorithm
    
    Returns:
    
    a cipher
    
    Throws:
    
    GeneralSecurityException - on error
  - getCipher
```
public static Cipher getCipher(String algorithm,
                               int mode,
                               Key key)
                        throws GeneralSecurityException
```
    Returns a cipher for the given encryption algorithm and key, possibly using the BC provider explicitly if the configured JCA providers cannot provide a cipher for the algorithm and key.
    
    Parameters:
    
    algorithm - the encryption algorithm
    
    mode - the mode of operation (encrypt or decrypt)
    
    key - the key
    
    Returns:
    
    a cipher
    
    Throws:
    
    GeneralSecurityException - on error
  - getKeyAgreement
```
public static KeyAgreement getKeyAgreement(String algorithm)
                                    throws GeneralSecurityException
```
    Returns a key agreement object for the given algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a key agreement for the algorithm.
    
    Parameters:
    
    algorithm - the key agreement algorithm
    
    Returns:
    
    a key agreement object
    
    Throws:
    
    GeneralSecurityException - on error
  - getKeyPairGenerator
```
public static KeyPairGenerator getKeyPairGenerator(String algorithm)
                                            throws GeneralSecurityException
```
    Returns a key pair generator for the given algorithm, possibly using the BC provider explicitly when the configured JCA providers cannot provide a generator for the algorithm.
    
    Parameters:
    
    algorithm - the algorithm
    
    Returns:
    
    a key pair generator
    
    Throws:
    
    GeneralSecurityException - on error
  - getMac
```
public static Mac getMac(String algorithm)
                  throws GeneralSecurityException
```
    Returns a MAC for the given algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a MAC for the algorithm.
    
    Parameters:
    
    algorithm - the MAC algorithm
    
    Returns:
    
    a MAC object
    
    Throws:
    
    GeneralSecurityException - on error
  - getMac
```
public static Mac getMac(String algorithm,
                         Key key)
                  throws GeneralSecurityException
```
    Returns a MAC for the given algorithm and key, possibly using the BC provider explicitly when the configured JCA providers cannot provide a MAC for the algorithm and key.
    
    Parameters:
    
    algorithm - the MAC algorithm
    
    key - the key
    
    Returns:
    
    a MAC object
    
    Throws:
    
    GeneralSecurityException - on error
  - getMessageDigest
```
public static MessageDigest getMessageDigest(String algorithm)
                                      throws GeneralSecurityException
```
    Returns a message digest for the given algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a message digest for the algorithm.
    
    Parameters:
    
    algorithm - the message digest algorithm
    
    Returns:
    
    a message digest object
    
    Throws:
    
    GeneralSecurityException - on error
  - getPublicKey
```
public static PublicKey getPublicKey(String algorithm,
                                     KeySpec keySpec)
                              throws GeneralSecurityException
```
    Returns a public key for the given algorithm and key specification, possibly using the BC provider explicitly when the configured JCA providers cannot provide a public key for the algorithm and key specification.
    
    Parameters:
    
    algorithm - the public key algorithm
    
    keySpec - the key specification
    
    Returns:
    
    a public key object
    
    Throws:
    
    GeneralSecurityException - on error
  - getSignature
```
public static Signature getSignature(String algorithm)
                              throws GeneralSecurityException
```
    Returns a signature for the given signature algorithm, possibly using the BC provider if the configured JCA providers cannot provide a signature.
    
    Parameters:
    
    algorithm - the signature algorithm
    
    Returns:
    
    a signature object
    
    Throws:
    
    GeneralSecurityException - on error
  - getCertificateFactory
```
public static CertificateFactory getCertificateFactory(String algorithm)
                                                throws GeneralSecurityException
```
    Returns a certificate factory object for the given certificate algorithm, possibly using the BC provider explicitly if the configured JCA providers cannot provide a certificate factory for the algorithm.
    
    Parameters:
    
    algorithm - the certificate algorithm
    
    Returns:
    
    a certificate factory
    
    Throws:
    
    GeneralSecurityException - on error
  - toOIDBytes
```
public static byte[] toOIDBytes(String oid)
```
    Encodes an object identifier. 0x80 Cryptographic mechanism reference. Object Identifier of the protocol to select (value only, tag 0x06 is omitted).
    
    Parameters:
    
    oid - the object identifier
    
    Returns:
    
    the encoding
  - partition
```
public static List<byte[]> partition(int segmentSize,
                                     byte[] data)
```
    Partitions a byte array into a number of segments of the given size, and a final segment if there is a remainder.
    
    Parameters:
    
    segmentSize - the number of bytes per segment
    
    data - the data to be partitioned
    
    Returns:
    
    a list with the segments
  - stripLeadingZeroes
```
public static byte[] stripLeadingZeroes(byte[] bytes)
```
    Strips any leading zeroes from a byte-array and returns the resulting byte-array.
    
    Parameters:
    
    bytes - the input byte-array (which is not modified in the process)
    
    Returns:
    
    a copy of the input byte-array, without the leading zeroes

Class Util

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

ENC_MODE

MAC_MODE

PACE_MODE

RFC5114_1024_160

RFC5114_2048_224

RFC5114_2048_256

Method Detail

getBouncyCastleProvider

deriveKey

deriveKey

deriveKey

deriveKey

computeKeySeed

computeKeySeed

pad

pad

unpad

recoverMessage

getRawECDSASignature

alignKeyDataToSize

i2os

i2os

os2i

os2i

os2fe

inferDigestAlgorithmFromSignatureAlgorithm

inferDigestAlgorithmFromCipherAlgorithmForKeyDerivation

toExplicitDHParameterSpec

getDetailedPublicKeyAlgorithm

getDetailedPrivateKeyAlgorithm

getCurveName

toExplicitECParameterSpec

toExplicitECParameterSpec

toECNamedCurveSpec

toSubjectPublicKeyInfo

toPublicKey

reconstructPublicKey

addMissingParametersToPublicKey

os2ECPoint

ecPoint2OS

inferProtocolIdentifier

add

multiply

isPointOnCurve

getBytes

getPrime

inferKeyAgreementAlgorithm

computeAffineY

toBouncyCastleECPoint

fromBouncyCastleECPoint

isValid

normalize

toBouncyECPublicKeyParameters

toBouncyECPrivateKeyParameters

toBouncyECDomainParameters

getCipher

getCipher

getKeyAgreement

getKeyPairGenerator

getMac

getMac

getMessageDigest

getPublicKey

getSignature

getCertificateFactory

toOIDBytes

partition

stripLeadingZeroes