Security · Explainer

What Is SHA-512?

What is SHA-512?

SHORT ANSWER

SHA-512 is a one-way cryptographic hash function from the SHA-2 family. It takes any input and produces a fixed 512-bit (64-byte) digest, typically displayed as 128 hexadecimal characters. It is used for data integrity, digital signatures, and checksums.

The basics

SHA-512 stands for Secure Hash Algorithm 512-bit. It was designed by the NSA and published by NIST in 2001 as part of the SHA-2 family. It processes input in 1024-bit blocks through 80 rounds of computation and produces a 512-bit digest.

Output length

SHA-512 always produces the same output size regardless of input size: 512 bits, which is 64 bytes, 128 hexadecimal characters, or approximately 88 Base64 characters.

  • 512 bits = 64 bytes
  • 128 hex characters
  • ~88 Base64 characters
  • Same output whether input is 1 byte or 1 GB

Block size and internals

SHA-512 processes data in 1024-bit (128-byte) blocks. Each block goes through 80 rounds of a compression function using 64-bit word operations. This makes it naturally efficient on 64-bit processors. The message schedule expands 16 words into 80 words per block.

What SHA-512 is used for

SHA-512 is used wherever data integrity and authenticity matter: verifying file downloads, digital signatures, TLS certificates, code signing, version control integrity (Git), and blockchain systems. It is not suitable for password storage due to its speed.

  • File integrity verification (checksums)
  • Digital signatures and certificates
  • Code signing
  • API payload verification
  • Version control integrity
  • NOT suitable for: password storage (use bcrypt)

SHA-512 vs SHA-256 at a glance

Both are SHA-2 family members. SHA-512 uses 64-bit words and 1024-bit blocks; SHA-256 uses 32-bit words and 512-bit blocks. SHA-512 produces a longer digest and can be faster on 64-bit hardware. SHA-256 is more compact and more widely adopted.

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FAQ

What is the output of SHA-512?

SHA-512 outputs 512 bits (64 bytes). In hexadecimal, that's 128 characters. In Base64, approximately 88 characters.

What is the block size of SHA-512?

SHA-512 processes input in 1024-bit (128-byte) blocks, using 80 rounds of compression per block.

What compression function does SHA-512 use?

SHA-512 uses a Merkle–Damgård construction with a Davies–Meyer compression function, processing 64-bit words through 80 rounds.

Is SHA-512 the same as SHA-2?

SHA-512 is a member of the SHA-2 family. SHA-2 includes SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256.