hash() — netty Function Reference

Architecture documentation for the hash() function in PseudoRandomFunction.java from the netty codebase.

Function java Buffer Allocators calls 1

Entity Profile

Buffer→ Allocators→ hash() — netty Function Reference

Dependency Diagram

graph TD
  a87902db_61fe_7a64_914d_ac398f987472["hash()"]
  431b76bc_7e00_cc48_26d9_b766666a6d12["PseudoRandomFunction"]
  a87902db_61fe_7a64_914d_ac398f987472 -->|defined in| 431b76bc_7e00_cc48_26d9_b766666a6d12
  78dde20e_4bff_6001_62fe_1c7953a28da7["concat()"]
  a87902db_61fe_7a64_914d_ac398f987472 -->|calls| 78dde20e_4bff_6001_62fe_1c7953a28da7
  style a87902db_61fe_7a64_914d_ac398f987472 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

handler/src/main/java/io/netty/handler/ssl/PseudoRandomFunction.java lines 63–87

    static byte[] hash(byte[] secret, byte[] label, byte[] seed, int length, String algo) {
        checkPositiveOrZero(length, "length");
        try {
            Mac hmac = Mac.getInstance(algo);
            hmac.init(new SecretKeySpec(secret, algo));
            /*
             * P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
             * HMAC_hash(secret, A(2) + seed) + HMAC_hash(secret, A(3) + seed) + ...
             * where + indicates concatenation. A() is defined as: A(0) = seed, A(i)
             * = HMAC_hash(secret, A(i-1))
             */

            int iterations = (int) Math.ceil(length / (double) hmac.getMacLength());
            byte[] expansion = EmptyArrays.EMPTY_BYTES;
            byte[] data = concat(label, seed);
            byte[] A = data;
            for (int i = 0; i < iterations; i++) {
                A = hmac.doFinal(A);
                expansion = concat(expansion, hmac.doFinal(concat(A, data)));
            }
            return Arrays.copyOf(expansion, length);
        } catch (GeneralSecurityException e) {
            throw new IllegalArgumentException("Could not find algo: " + algo, e);
        }
    }