What is Winternitz One Time Signature Scheme?

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Winternitz One Time Signature Scheme

Robert Winternitz proposed the W-OTS approach. It is thought to be quantum resilient since it uses modest key and signature sizes.

  • It generates 32 ☓ 256 bit random private keys in total.

  • We then have this a number of times, and a parameter (W) is used to define them.

  • We can hash the private keys by using W = 8(2W).

  • It generates public keys with a length of 32 256-bits

  • The signature is formed by taking 8-bits at a time, subtracting the 8-bit binary int (n) from 256, then hashing the private key 256 times.

  • Thereafter, the signature is made up of 32 hashes created from random private keys.

How Does It Work?

The procedure is as follows −

  • We start by making 32 256-bit random numbers. Our private key will be made up of these 32 values.

  • Each of these values is then hashed 256 times. Our public key will be made up of these 32 values.

  • We're now going to hash the message with SHA-256. This will yield 32 8-bit values (N1, N2,..., N32).

  • For the signature, we hash each 8-bit value in the message's hash 256-N times (where N is the value of the 8-bit value).

  • The message is hashed with SHA-256, and each 8-bit value is used to prove the signature. The message hash value specifies how many times the 8-bit signature value is hashed (N1N2)... The result of each action should be the same as the public key value.

Key Generation

  • A pair of keys is to be generated, a private key and a public key

  • Using a random number generator, 32 256-bit random numbers are generated to create the private key.

  • Each of the 32 numbers is hashed 256 times to get another set of 32 256-bit numbers for the public key. The public key is available to anyone.

Signature Generation

  • SHA 256 is used to hash the message, resulting in a 256-bit digest. This hash is broken down into 32 8-bit values (N1N2N3...N32).

  • 256-N times hashes each 8-bit value, where N is the value of the 8-bit value. For example, if N1 is an 8-bit number of 10001000 = 136, then N1 will be hashed 256 - 136 = 120 times. The digital signature is created after performing this operation for each of the 8-bit values.

Signature Verification

  • SHA-256 is used to generate a digest of 32 8-bit values (N1N2N3...N32). from the message.

  • The signature value is then hashed by the number of times the message hash value (N1N2N3...N32) specifies.

  • The signature is then compared to the public key, and if the two matches, the signature is considered legitimate.

Updated on 05-Nov-2021 11:27:51