com.google.crypto.tink.signature.internal

Class SigUtil

java.lang.Object

com.google.crypto.tink.signature.internal.SigUtil

public final class SigUtil
extends Object

Utility functions to convert to and from signature-related proto.

Method Summary

Modifier and Type	Method and Description
static EllipticCurves.CurveType	toCurveType(EllipticCurveType type) Converts protobuf enum EllipticCurveType to raw Java enum {code CurveType}.
static EllipticCurves.EcdsaEncoding	toEcdsaEncoding(EcdsaSignatureEncoding encoding) Converts protobuf enum EcdsaSignatureEncoding to raw Java enum {code EllipticCurves.EcdsaEncoding}.
static Enums.HashType	toHashType(HashType hash) Converts protobuf enum HashType to raw Java enum Enums.HashType.
static com.google.protobuf.ByteString	toUnsignedIntByteString(BigInteger i) Returns the unsigned byte representation of the input BigInteger.
static void	validateEcdsaParams(EcdsaParams params) Validates Ecdsa's parameters.
static void	validateRsaSsaPkcs1Params(RsaSsaPkcs1Params params) Validates RsaSsaPkcs1's parameters.
static void	validateRsaSsaPssParams(RsaSsaPssParams params) Validates RsaSsaPss's parameters.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

validateEcdsaParams

public static void validateEcdsaParams(EcdsaParams params)
                                throws GeneralSecurityException

Validates Ecdsa's parameters. The hash's strength must not be weaker than the curve's strength.

Parameters:

params - the Ecdsa's parameters protocol buffer.

Throws:

GeneralSecurityException - iff it's invalid.

validateRsaSsaPkcs1Params

public static void validateRsaSsaPkcs1Params(RsaSsaPkcs1Params params)
                                      throws GeneralSecurityException

Validates RsaSsaPkcs1's parameters. As SHA1 is unsafe, we will only support SHA256 and SHA512 for digital signature.

Parameters:

params - the RsaSsaPkcs1Params protocol buffer.

Throws:

GeneralSecurityException - iff it's invalid.

validateRsaSsaPssParams

public static void validateRsaSsaPssParams(RsaSsaPssParams params)
                                    throws GeneralSecurityException

Validates RsaSsaPss's parameters.

• The MGF1 hash function must be the same as the signature hash function.
• The hash function used must be either SHA256, SHA384, or SHA512.
• The salt length must be non-zero.

Parameters:

params - the RsaSsaPssParams protocol buffer.

Throws:

GeneralSecurityException - iff it's invalid.

toHashType

public static Enums.HashType toHashType(HashType hash)
                                 throws GeneralSecurityException

Converts protobuf enum HashType to raw Java enum Enums.HashType.

Throws:

GeneralSecurityException - if the HashType is not SHA256, SHA384, or SHA512.

toCurveType

public static EllipticCurves.CurveType toCurveType(EllipticCurveType type)
                                            throws GeneralSecurityException

Converts protobuf enum EllipticCurveType to raw Java enum {code CurveType}.

Throws:

GeneralSecurityException

toEcdsaEncoding

public static EllipticCurves.EcdsaEncoding toEcdsaEncoding(EcdsaSignatureEncoding encoding)
                                                    throws GeneralSecurityException

Converts protobuf enum EcdsaSignatureEncoding to raw Java enum {code EllipticCurves.EcdsaEncoding}.

Throws:

GeneralSecurityException

toUnsignedIntByteString

public static com.google.protobuf.ByteString toUnsignedIntByteString(BigInteger i)

Returns the unsigned byte representation of the input BigInteger. BigInteger's toByteArray returns a two's complement representation of non-negative integers, which might include an extra zero byte at position 0 (in big endian).