libcryfs/vendor/scrypt-1.2.0/FORMAT

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scrypt encrypted data format
----------------------------
offset length
0 6 "scrypt"
6 1 scrypt data file version number (== 0)
7 1 log2(N) (must be between 1 and 63 inclusive)
8 4 r (big-endian integer; must satisfy r * p < 2^30)
12 4 p (big-endian integer; must satisfy r * p < 2^30)
16 32 salt
48 16 first 16 bytes of SHA256(bytes 0 .. 47)
64 32 HMAC-SHA256(bytes 0 .. 63)
96 X data xor AES256-CTR key stream generated with nonce == 0
96+X 32 HMAC-SHA256(bytes 0 .. 96 + (X - 1))
AES256-CTR is computed with a 256-bit AES key key_enc, and HMAC-SHA256 is
computed with a 256-bit key key_hmac, where
scrypt(password, salt, N, r, p, 64) == [key_enc][key_hmac]