JH is acryptographic hash function submitted to theNIST hash function competition by Hongjun Wu. Though chosen as one of the five finalists of the competition, in 2012 JH ultimately lost to NIST hash candidateKeccak.^[2] JH has a 1024-bit state, and works on 512-bit input blocks. Processing an input block consists of three steps:

1. XOR the input block into the left half of the state.
2. Apply a 42-round unkeyed permutation (encryption function) to the state. This consists of 42 repetitions of:
   1. Break the input into 256 4-bit blocks, and map each through one of two 4-bitS-boxes, the choice being made by a 256-bit round-dependent key schedule. Equivalently, combine each input block with a key bit, and map the result through a 5→4 bit S-box.
   2. Mix adjacent 4-bit blocks using amaximum distance separable code overGF(2⁴).
   3. Permute 4-bit blocks so that they will be adjacent to different blocks in following rounds.
3. XOR the input block into the right half of the state.

The resulting digest is the last 224, 256, 384 or 512 bits from the 1024-bit final value.It is well suited to abit slicing implementation using theSSE2 instruction set, giving speeds of 16.8cycles per byte.

Hash values of empty string.

JH-224("")0x 2c99df889b019309051c60fecc2bd285a774940e43175b76b2626630JH-256("")0x 46e64619c18bb0a92a5e87185a47eef83ca747b8fcc8e1412921357e326df434JH-384("")0x 2fe5f71b1b3290d3c017fb3c1a4d02a5cbeb03a0476481e25082434a881994b0ff99e078d2c16b105ad069b569315328JH-512("")0x 90ecf2f76f9d2c8017d979ad5ab96b87d58fc8fc4b83060f3f900774faa2c8fabe69c5f4ff1ec2b61d6b316941cedee117fb04b1f4c5bc1b919ae841c50eec4f

Even a small change in the message will (with overwhelming probability) result in a mostly different hash, due to theavalanche effect. For example, adding a period to the end of the sentence:

JH-256("The quick brown fox jumps over the lazy dog")0x 6a049fed5fc6874acfdc4a08b568a4f8cbac27de933496f031015b38961608a0JH-256("The quick brown fox jumps over the lazy dog.")0x d001ae2315421c5d3272bac4f4aa524bddd207530d5d26bbf51794f0da18fafc

• The JH web siteArchived 2011-12-04 at theWayback Machine
• JH page on the SHA-3 Zoo
• VHDL source code developed by the Cryptographic Engineering Research Group (CERG) at George Mason University

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