SHA384 hash

 

About SHA384 hash

SHA-384 (Secure Hash Algorithm 384-bit) is a member of the SHA-2 family of cryptographic hash functions. It is designed to produce a longer hash value compared to SHA-256, offering increased security by providing a 384-bit output.

Characteristics of SHA-384

  1. Fixed-Length Output:

    • SHA-384 produces a fixed-length output of 384 bits (48 bytes), regardless of the input data's length.

  2. Input Padding:

    • Similar to SHA-256, the input message for SHA-384 is padded so that its length is congruent to 896 modulo 1024. Padding involves appending a single '1' bit, followed by '0' bits until the message length is 128 bits short of a multiple of 1024. The length of the original message (before padding) is then appended as a 128-bit integer.

  3. Processing in Blocks:

    • SHA-384 processes the input message in 1024-bit (128-byte) blocks.

  4. Initialization Vector (IV):

    • SHA-384 starts with a predefined initial state composed of eight 64-bit words:
      • H0 = 0xCBBB9D5DC1059ED8
      • H1 = 0x629A292A367CD507
      • H2 = 0x9159015A3070DD17
      • H3 = 0x152FECD8F70E5939
      • H4 = 0x67332667FFC00B31
      • H5 = 0x8EB44A8768581511
      • H6 = 0xDB0C2E0D64F98FA7
      • H7 = 0x47B5481DBEFA4FA4

  5. Compression Function:

    • The SHA-384 compression function is similar to SHA-512, involving 80 rounds of processing for each 1024-bit block. Each round uses different logical functions, constants, and message schedule operations:
      • Logical functions include bitwise operations (AND, OR, XOR, NOT), additions, and shifts/rotations.
      • Constants are derived from the first 64 bits of the fractional parts of the cube roots of the first 80 prime numbers.

Algorithm Steps

  1. Initialization:

    • Initialize the state variables (H0 to H7) to the predefined values.

  2. Padding:

    • Pad the input message according to the specified padding rules.

  3. Processing:

    • Divide the padded message into 1024-bit blocks.
    • For each block, perform the 80 iterations of the compression function, updating the state variables.

  4. Output:

    • After processing all blocks, concatenate the state variables (H0 to H5) to produce the final 384-bit hash value.

Security and Usage

  • Security:

    • Collision Resistance: SHA-384 provides strong collision resistance due to its longer output size, making it extremely difficult for two different inputs to produce the same hash output.
    • Preimage Resistance: SHA-384 is resistant to preimage attacks, making it computationally infeasible to find an input that hashes to a given output.
    • Second-Preimage Resistance: SHA-384 also offers strong resistance to second-preimage attacks, ensuring that it is difficult to find a second input with the same hash as a given input.
    • SHA-384's longer output size provides additional security margin compared to SHA-256, particularly in applications requiring high resistance to collision attacks.

  • Usage:

    • SHA-384 is used in various security-critical applications where a longer hash value is desirable, including digital signatures, SSL/TLS certificates, and data integrity verification.
    • It is particularly suitable for applications that require a higher level of security assurance and where the additional computational overhead of processing larger blocks is acceptable.

Summary

SHA-384 is a cryptographic hash function in the SHA-2 family that produces a 384-bit hash value. It offers strong security properties, including resistance to collisions, preimage attacks, and second-preimage attacks. SHA-384 is used in applications that benefit from its longer hash output, providing increased security assurance compared to shorter hash functions like SHA-256. Its robust security and suitability for various cryptographic applications make it a valuable choice in modern security protocols and systems.