1 // Copyright 2011 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Package crypto collects common cryptographic constants. 6 package crypto 7 8 import ( 9 "hash" 10 "io" 11 "strconv" 12 ) 13 14 // Hash identifies a cryptographic hash function that is implemented in another 15 // package. 16 type Hash uint 17 18 // HashFunc simply returns the value of h so that Hash implements SignerOpts. 19 func (h Hash) HashFunc() Hash { 20 return h 21 } 22 23 const ( 24 MD4 Hash = 1 + iota // import golang.org/x/crypto/md4 25 MD5 // import crypto/md5 26 SHA1 // import crypto/sha1 27 SHA224 // import crypto/sha256 28 SHA256 // import crypto/sha256 29 SHA384 // import crypto/sha512 30 SHA512 // import crypto/sha512 31 MD5SHA1 // no implementation; MD5+SHA1 used for TLS RSA 32 RIPEMD160 // import golang.org/x/crypto/ripemd160 33 SHA3_224 // import golang.org/x/crypto/sha3 34 SHA3_256 // import golang.org/x/crypto/sha3 35 SHA3_384 // import golang.org/x/crypto/sha3 36 SHA3_512 // import golang.org/x/crypto/sha3 37 SHA512_224 // import crypto/sha512 38 SHA512_256 // import crypto/sha512 39 maxHash 40 ) 41 42 var digestSizes = []uint8{ 43 MD4: 16, 44 MD5: 16, 45 SHA1: 20, 46 SHA224: 28, 47 SHA256: 32, 48 SHA384: 48, 49 SHA512: 64, 50 SHA512_224: 28, 51 SHA512_256: 32, 52 SHA3_224: 28, 53 SHA3_256: 32, 54 SHA3_384: 48, 55 SHA3_512: 64, 56 MD5SHA1: 36, 57 RIPEMD160: 20, 58 } 59 60 // Size returns the length, in bytes, of a digest resulting from the given hash 61 // function. It doesn't require that the hash function in question be linked 62 // into the program. 63 func (h Hash) Size() int { 64 if h > 0 && h < maxHash { 65 return int(digestSizes[h]) 66 } 67 panic("crypto: Size of unknown hash function") 68 } 69 70 var hashes = make([]func() hash.Hash, maxHash) 71 72 // New returns a new hash.Hash calculating the given hash function. New panics 73 // if the hash function is not linked into the binary. 74 func (h Hash) New() hash.Hash { 75 if h > 0 && h < maxHash { 76 f := hashes[h] 77 if f != nil { 78 return f() 79 } 80 } 81 panic("crypto: requested hash function #" + strconv.Itoa(int(h)) + " is unavailable") 82 } 83 84 // Available reports whether the given hash function is linked into the binary. 85 func (h Hash) Available() bool { 86 return h < maxHash && hashes[h] != nil 87 } 88 89 // RegisterHash registers a function that returns a new instance of the given 90 // hash function. This is intended to be called from the init function in 91 // packages that implement hash functions. 92 func RegisterHash(h Hash, f func() hash.Hash) { 93 if h >= maxHash { 94 panic("crypto: RegisterHash of unknown hash function") 95 } 96 hashes[h] = f 97 } 98 99 // PublicKey represents a public key using an unspecified algorithm. 100 type PublicKey interface{} 101 102 // PrivateKey represents a private key using an unspecified algorithm. 103 type PrivateKey interface{} 104 105 // Signer is an interface for an opaque private key that can be used for 106 // signing operations. For example, an RSA key kept in a hardware module. 107 type Signer interface { 108 // Public returns the public key corresponding to the opaque, 109 // private key. 110 Public() PublicKey 111 112 // Sign signs digest with the private key, possibly using entropy from 113 // rand. For an RSA key, the resulting signature should be either a 114 // PKCS#1 v1.5 or PSS signature (as indicated by opts). For an (EC)DSA 115 // key, it should be a DER-serialised, ASN.1 signature structure. 116 // 117 // Hash implements the SignerOpts interface and, in most cases, one can 118 // simply pass in the hash function used as opts. Sign may also attempt 119 // to type assert opts to other types in order to obtain algorithm 120 // specific values. See the documentation in each package for details. 121 // 122 // Note that when a signature of a hash of a larger message is needed, 123 // the caller is responsible for hashing the larger message and passing 124 // the hash (as digest) and the hash function (as opts) to Sign. 125 Sign(rand io.Reader, digest []byte, opts SignerOpts) (signature []byte, err error) 126 } 127 128 // SignerOpts contains options for signing with a Signer. 129 type SignerOpts interface { 130 // HashFunc returns an identifier for the hash function used to produce 131 // the message passed to Signer.Sign, or else zero to indicate that no 132 // hashing was done. 133 HashFunc() Hash 134 } 135 136 // Decrypter is an interface for an opaque private key that can be used for 137 // asymmetric decryption operations. An example would be an RSA key 138 // kept in a hardware module. 139 type Decrypter interface { 140 // Public returns the public key corresponding to the opaque, 141 // private key. 142 Public() PublicKey 143 144 // Decrypt decrypts msg. The opts argument should be appropriate for 145 // the primitive used. See the documentation in each implementation for 146 // details. 147 Decrypt(rand io.Reader, msg []byte, opts DecrypterOpts) (plaintext []byte, err error) 148 } 149 150 type DecrypterOpts interface{} 151
