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Diffstat (limited to 'vendor/golang.org/x/crypto/pkcs12/pbkdf.go')
| -rw-r--r-- | vendor/golang.org/x/crypto/pkcs12/pbkdf.go | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/pkcs12/pbkdf.go b/vendor/golang.org/x/crypto/pkcs12/pbkdf.go new file mode 100644 index 0000000..5c419d4 --- /dev/null +++ b/vendor/golang.org/x/crypto/pkcs12/pbkdf.go @@ -0,0 +1,170 @@ +// Copyright 2015 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package pkcs12 + +import ( + "bytes" + "crypto/sha1" + "math/big" +) + +var ( + one = big.NewInt(1) +) + +// sha1Sum returns the SHA-1 hash of in. +func sha1Sum(in []byte) []byte { + sum := sha1.Sum(in) + return sum[:] +} + +// fillWithRepeats returns v*ceiling(len(pattern) / v) bytes consisting of +// repeats of pattern. +func fillWithRepeats(pattern []byte, v int) []byte { + if len(pattern) == 0 { + return nil + } + outputLen := v * ((len(pattern) + v - 1) / v) + return bytes.Repeat(pattern, (outputLen+len(pattern)-1)/len(pattern))[:outputLen] +} + +func pbkdf(hash func([]byte) []byte, u, v int, salt, password []byte, r int, ID byte, size int) (key []byte) { + // implementation of https://tools.ietf.org/html/rfc7292#appendix-B.2 , RFC text verbatim in comments + + // Let H be a hash function built around a compression function f: + + // Z_2^u x Z_2^v -> Z_2^u + + // (that is, H has a chaining variable and output of length u bits, and + // the message input to the compression function of H is v bits). The + // values for u and v are as follows: + + // HASH FUNCTION VALUE u VALUE v + // MD2, MD5 128 512 + // SHA-1 160 512 + // SHA-224 224 512 + // SHA-256 256 512 + // SHA-384 384 1024 + // SHA-512 512 1024 + // SHA-512/224 224 1024 + // SHA-512/256 256 1024 + + // Furthermore, let r be the iteration count. + + // We assume here that u and v are both multiples of 8, as are the + // lengths of the password and salt strings (which we denote by p and s, + // respectively) and the number n of pseudorandom bits required. In + // addition, u and v are of course non-zero. + + // For information on security considerations for MD5 [19], see [25] and + // [1], and on those for MD2, see [18]. + + // The following procedure can be used to produce pseudorandom bits for + // a particular "purpose" that is identified by a byte called "ID". + // This standard specifies 3 different values for the ID byte: + + // 1. If ID=1, then the pseudorandom bits being produced are to be used + // as key material for performing encryption or decryption. + + // 2. If ID=2, then the pseudorandom bits being produced are to be used + // as an IV (Initial Value) for encryption or decryption. + + // 3. If ID=3, then the pseudorandom bits being produced are to be used + // as an integrity key for MACing. + + // 1. Construct a string, D (the "diversifier"), by concatenating v/8 + // copies of ID. + var D []byte + for i := 0; i < v; i++ { + D = append(D, ID) + } + + // 2. Concatenate copies of the salt together to create a string S of + // length v(ceiling(s/v)) bits (the final copy of the salt may be + // truncated to create S). Note that if the salt is the empty + // string, then so is S. + + S := fillWithRepeats(salt, v) + + // 3. Concatenate copies of the password together to create a string P + // of length v(ceiling(p/v)) bits (the final copy of the password + // may be truncated to create P). Note that if the password is the + // empty string, then so is P. + + P := fillWithRepeats(password, v) + + // 4. Set I=S||P to be the concatenation of S and P. + I := append(S, P...) + + // 5. Set c=ceiling(n/u). + c := (size + u - 1) / u + + // 6. For i=1, 2, ..., c, do the following: + A := make([]byte, c*20) + var IjBuf []byte + for i := 0; i < c; i++ { + // A. Set A2=H^r(D||I). (i.e., the r-th hash of D||1, + // H(H(H(... H(D||I)))) + Ai := hash(append(D, I...)) + for j := 1; j < r; j++ { + Ai = hash(Ai) + } + copy(A[i*20:], Ai[:]) + + if i < c-1 { // skip on last iteration + // B. Concatenate copies of Ai to create a string B of length v + // bits (the final copy of Ai may be truncated to create B). + var B []byte + for len(B) < v { + B = append(B, Ai[:]...) + } + B = B[:v] + + // C. Treating I as a concatenation I_0, I_1, ..., I_(k-1) of v-bit + // blocks, where k=ceiling(s/v)+ceiling(p/v), modify I by + // setting I_j=(I_j+B+1) mod 2^v for each j. + { + Bbi := new(big.Int).SetBytes(B) + Ij := new(big.Int) + + for j := 0; j < len(I)/v; j++ { + Ij.SetBytes(I[j*v : (j+1)*v]) + Ij.Add(Ij, Bbi) + Ij.Add(Ij, one) + Ijb := Ij.Bytes() + // We expect Ijb to be exactly v bytes, + // if it is longer or shorter we must + // adjust it accordingly. + if len(Ijb) > v { + Ijb = Ijb[len(Ijb)-v:] + } + if len(Ijb) < v { + if IjBuf == nil { + IjBuf = make([]byte, v) + } + bytesShort := v - len(Ijb) + for i := 0; i < bytesShort; i++ { + IjBuf[i] = 0 + } + copy(IjBuf[bytesShort:], Ijb) + Ijb = IjBuf + } + copy(I[j*v:(j+1)*v], Ijb) + } + } + } + } + // 7. Concatenate A_1, A_2, ..., A_c together to form a pseudorandom + // bit string, A. + + // 8. Use the first n bits of A as the output of this entire process. + return A[:size] + + // If the above process is being used to generate a DES key, the process + // should be used to create 64 random bits, and the key's parity bits + // should be set after the 64 bits have been produced. Similar concerns + // hold for 2-key and 3-key triple-DES keys, for CDMF keys, and for any + // similar keys with parity bits "built into them". +} |