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feat(pbkdf2): allow use of int64 #98

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Merged
james-d-elliott merged 2 commits into from
Dec 24, 2025
Merged

feat(pbkdf2): allow use of int64 #98

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feat(pbkdf2): allow use of int64
james-d-elliott Dec 21, 2025
ce2af19
Merge branch 'master' into feat-pbkdf2-int64
james-d-elliott Dec 24, 2025
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13 changes: 9 additions & 4 deletions pbkdf2/pbkdf2.go
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Original file line number Diff line number Diff line change
Expand Up @@ -40,14 +40,19 @@ import (
// Using a higher iteration count will increase the cost of an exhaustive
// search but will also make derivation proportionally slower.
func Key(password, salt []byte, iter, keyLen int, h func() hash.Hash) []byte {
return KeyExtended(password, salt, int64(iter), int64(keyLen), h)
}

// KeyExtended is the same as Key but allows the use of int64 inputs.
func KeyExtended(password, salt []byte, iter, keyLen int64, h func() hash.Hash) []byte {
prf := hmac.New(h, password)
hashLen := prf.Size()
hashLen := int64(prf.Size())
numBlocks := (keyLen + hashLen - 1) / hashLen

var buf [4]byte
dk := make([]byte, 0, numBlocks*hashLen)
U := make([]byte, hashLen)
for block := 1; block <= numBlocks; block++ {
for block := int64(1); block <= numBlocks; block++ {
// N.B.: || means concatenation, ^ means XOR
// for each block T_i = U_1 ^ U_2 ^ ... ^ U_iter
// U_1 = PRF(password, salt || uint(i))
Expand All @@ -59,11 +64,11 @@ func Key(password, salt []byte, iter, keyLen int, h func() hash.Hash) []byte {
buf[3] = byte(block)
prf.Write(buf[:4])
dk = prf.Sum(dk)
T := dk[len(dk)-hashLen:]
T := dk[int64(len(dk))-hashLen:]
copy(U, T)

// U_n = PRF(password, U_(n-1))
for n := 2; n <= iter; n++ {
for n := int64(2); n <= iter; n++ {
prf.Reset()
prf.Write(U)
U = U[:0]
Expand Down