public class DigestService
The DigestService class is a service that offers the main crypto methods for calculating transaction hashes and
building Merkle trees. The default
instance is passed by default to instances of classes like TransactionBuilder
and as a parameter to MerkleTree.getMerkleTree(...) method. In future the default
instance can be parametrized
to initialize with the network default hash algorithm or just a more secure algorithm (e.g. SHA3_256). While the
SHA2_256 is vulnerable to pre-image attacks, the computeNonce and componentHash methods behaviour is defined by
the hashTwiceNonce and hashTwiceComponent; with SHA2_256 they both must be set to true to ensure pre-image attack
won't work (and for backward compatibility), but for other algorithms like SHA3_256 that are not affected, they
can and should be set to false as hashing twice would not improve security but affect performance.
public DigestService(@NotNull java.lang.String hashAlgorithm)
The DigestService class is a service that offers the main crypto methods for calculating transaction hashes and
building Merkle trees. The default
instance is passed by default to instances of classes like TransactionBuilder
and as a parameter to MerkleTree.getMerkleTree(...) method. In future the default
instance can be parametrized
to initialize with the network default hash algorithm or just a more secure algorithm (e.g. SHA3_256). While the
SHA2_256 is vulnerable to pre-image attacks, the computeNonce and componentHash methods behaviour is defined by
the hashTwiceNonce and hashTwiceComponent; with SHA2_256 they both must be set to true to ensure pre-image attack
won't work (and for backward compatibility), but for other algorithms like SHA3_256 that are not affected, they
can and should be set to false as hashing twice would not improve security but affect performance.
public int getDigestLength()
Specifies the WORD size for the given hash algorithm.
@NotNull public SecureHash hash(@NotNull kotlin.Array[] bytes)
Computes the digest of the ByteArray.
@NotNull public SecureHash hash(@NotNull java.lang.String str)
Computes the digest of the String's UTF-8 byte contents.
@NotNull public SecureHash getAllOnesHash()
A digest value consisting of 0xFF bytes.
@NotNull public SecureHash getZeroHash()
A hash value consisting of 0x00 bytes.
@NotNull public SecureHash componentHash(@NotNull OpaqueBytes opaqueBytes, @NotNull PrivacySalt privacySalt, int componentGroupIndex, int internalIndex)
Compute the hash of each serialised component so as to be used as Merkle tree leaf. The resultant output (leaf) is
calculated using the service's hash algorithm, thus HASH(HASH(nonce || serializedComponent)) for SHA2-256 and other
algorithms loaded via JCA MessageDigest, or DigestAlgorithm.componentDigest(nonce || serializedComponent)
otherwise, where nonce is computed from computeNonce
.
computeNonce
@NotNull public SecureHash componentHash(@NotNull SecureHash nonce, @NotNull OpaqueBytes opaqueBytes)
Return the HASH(HASH(nonce || serializedComponent)) for SHA2-256 and other algorithms loaded via JCA MessageDigest, otherwise it's defined by DigestAlgorithm.componentDigest(nonce || serializedComponent).
@NotNull public <T> SecureHash serializedHash(@NotNull T x)
Serialise the object and return the hash of the serialized bytes. Note that the resulting hash may not be deterministic across platform versions: serialization can produce different values if any of the types being serialized have changed, or if the version of serialization specified by the context changes.
@NotNull public SecureHash computeNonce(@NotNull PrivacySalt privacySalt, int groupIndex, int internalIndex)
Method to compute a nonce based on privacySalt, component group index and component internal index. SHA256d (double SHA256) is used to prevent length extension attacks.
privacySalt
- a class PrivacySalt
.groupIndex
- the fixed index (ordinal) of this component group.internalIndex
- the internal index of this object in its corresponding components list.@NotNull public java.lang.String getHashAlgorithm()
the name of the hash algorithm to be used for the instance
@NotNull public java.lang.String component1()
the name of the hash algorithm to be used for the instance
@NotNull public DigestService copy(@NotNull java.lang.String hashAlgorithm)
The DigestService class is a service that offers the main crypto methods for calculating transaction hashes and
building Merkle trees. The default
instance is passed by default to instances of classes like TransactionBuilder
and as a parameter to MerkleTree.getMerkleTree(...) method. In future the default
instance can be parametrized
to initialize with the network default hash algorithm or just a more secure algorithm (e.g. SHA3_256). While the
SHA2_256 is vulnerable to pre-image attacks, the computeNonce and componentHash methods behaviour is defined by
the hashTwiceNonce and hashTwiceComponent; with SHA2_256 they both must be set to true to ensure pre-image attack
won't work (and for backward compatibility), but for other algorithms like SHA3_256 that are not affected, they
can and should be set to false as hashing twice would not improve security but affect performance.
@NotNull public java.lang.String toString()
The DigestService class is a service that offers the main crypto methods for calculating transaction hashes and
building Merkle trees. The default
instance is passed by default to instances of classes like TransactionBuilder
and as a parameter to MerkleTree.getMerkleTree(...) method. In future the default
instance can be parametrized
to initialize with the network default hash algorithm or just a more secure algorithm (e.g. SHA3_256). While the
SHA2_256 is vulnerable to pre-image attacks, the computeNonce and componentHash methods behaviour is defined by
the hashTwiceNonce and hashTwiceComponent; with SHA2_256 they both must be set to true to ensure pre-image attack
won't work (and for backward compatibility), but for other algorithms like SHA3_256 that are not affected, they
can and should be set to false as hashing twice would not improve security but affect performance.
public int hashCode()
The DigestService class is a service that offers the main crypto methods for calculating transaction hashes and
building Merkle trees. The default
instance is passed by default to instances of classes like TransactionBuilder
and as a parameter to MerkleTree.getMerkleTree(...) method. In future the default
instance can be parametrized
to initialize with the network default hash algorithm or just a more secure algorithm (e.g. SHA3_256). While the
SHA2_256 is vulnerable to pre-image attacks, the computeNonce and componentHash methods behaviour is defined by
the hashTwiceNonce and hashTwiceComponent; with SHA2_256 they both must be set to true to ensure pre-image attack
won't work (and for backward compatibility), but for other algorithms like SHA3_256 that are not affected, they
can and should be set to false as hashing twice would not improve security but affect performance.
public boolean equals(@Nullable java.lang.Object p)
The DigestService class is a service that offers the main crypto methods for calculating transaction hashes and
building Merkle trees. The default
instance is passed by default to instances of classes like TransactionBuilder
and as a parameter to MerkleTree.getMerkleTree(...) method. In future the default
instance can be parametrized
to initialize with the network default hash algorithm or just a more secure algorithm (e.g. SHA3_256). While the
SHA2_256 is vulnerable to pre-image attacks, the computeNonce and componentHash methods behaviour is defined by
the hashTwiceNonce and hashTwiceComponent; with SHA2_256 they both must be set to true to ensure pre-image attack
won't work (and for backward compatibility), but for other algorithms like SHA3_256 that are not affected, they
can and should be set to false as hashing twice would not improve security but affect performance.