Hash Credential

Overview

The create_hash function generates a cryptographic hash using one of the supported algorithms. It returns a Result containing either the generated hash as a String or an error using the anyhow library for extended error handling.

Function Definition

pub(crate) fn create_hash(value: Value<Testnet3>, algorithm: HashAlgorithm) -> Result<String, anyhow::Error>;

Parameters:

• value: The value you want to hash, of type Value<Testnet3>.

• algorithm: An enum representing the hashing algorithm to be used (HashAlgorithm).

Returns:

• Result<String, anyhow::Error>: A Result that will either contain the generated hash as a String or an error.

Hash Calculation Steps

• Conversion: The value is first converted into either fields or bits based on the algorithm selected.

• Hashing: The Testnet3 object exposes static methods to generate hashes based on the selected algorithm. These methods return a Result and can fail, leading to error propagation.

• Final Conversion: For some algorithms, additional steps like converting to a group and then back to a field are performed.

Hash Types

Name	Rust	Leo
Poseidon2	Testnet3::hash_psd2(x)	Poseidon2::hash_to_field(x)
BHP	Testnet3::hash_bhp1024(x)	BHP1024::hash_to_field(x)
Keccak	Testnet3::hash_keccak256(x)	Keccak256::hash_to_field(x)
SHA3	Testnet3::hash_sha3_256(x)	SHA3_256::hash_to_field(x)

Hash Credential

// This function creates a cryptographic hash of a given value, using the specified hash algorithm.
// It returns a string representation of the hash or an error.
pub(crate) fn create_hash(value: Value<Testnet3>, algorithm: HashAlgorithm) -> Result<String, anyhow::Error> {
    
    // Generate the hash based on the selected algorithm
    let hash = match algorithm {
        
        // POSEIDON2 algorithm
        HashAlgorithm::POSEIDON2 => {
            // Convert the value to a fields object
            let message = value.to_fields()
                .map_err(|e| anyhow!("Failed value to Fields conversion: {}", e))?;
            
            // Perform the POSEIDON2 hash conversion
            let hash = Testnet3::hash_psd2(message.as_slice())
                .map_err(|e| anyhow!("Failed hash_psd2 conversion: {}", e))?;
            
            // Convert the hash to a string representation
            hash.to_string()
        },
        
        // BHP1024 algorithm
        HashAlgorithm::BHP1024 => {
            // Convert the value to bits in little-endian
            let message = value.to_bits_le();
            
            // Perform the BHP1024 hash conversion
            let hash = Testnet3::hash_bhp1024(message.as_slice())
                .map_err(|e| anyhow!("Failed hash_bhp1024 conversion: {}", e))?;
            
            // Convert the hash to a string representation
            hash.to_string()
        },
        
        // SHA3_256 algorithm
        HashAlgorithm::SHA3_256 => {
            // Convert the value to bits in little-endian
            let message = value.to_bits_le();
            
            // Generate SHA3-256 hash from the message bits
            let sha_bit_vec = Testnet3::hash_sha3_256(message.as_slice())
                .map_err(|e| anyhow!("Failed hash_sha3_256 conversion: {}", e))?;
            
            // Convert SHA3-256 hash to a group using BHP256
            let bhp_group = Testnet3::hash_to_group_bhp256(sha_bit_vec.as_slice())
                .map_err(|e| anyhow!("Failed hash_to_group_bhp256 conversion: {}", e))?;
            
            // Convert the group to a literal
            let literal_group_from_bhp = Literal::Group(bhp_group);
            
            // Cast the group literal to a field
            let casted_to_field = literal_group_from_bhp
                .cast_lossy(snarkvm::prelude::LiteralType::Field)
                .map_err(|e| anyhow!("Failed cast_lossy conversion: {}", e))?;
            
            // Convert the hash to a string representation
            casted_to_field.to_string()
        },
        
        // KECCAK256 algorithm
        HashAlgorithm::KECCAK256 => {
            // Convert the value to bits in little-endian
            let message = value.to_bits_le();
            
            // Generate Keccak-256 hash from the message bits
            let keccak_bit_vec = Testnet3::hash_keccak256(message.as_slice())
                .map_err(|e| anyhow!("Failed hash_keccak256 conversion: {}", e))?;
            
            // Convert Keccak-256 hash to a group using BHP256
            let bhp_group = Testnet3::hash_to_group_bhp256(keccak_bit_vec.as_slice())
                .map_err(|e| anyhow!("Failed hash_to_group_bhp256 conversion: {}", e))?;
            
            // Convert the group to a literal
            let literal_group_from_bhp = Literal::Group(bhp_group);
            
            // Cast the group literal to a field
            let casted_to_field = literal_group_from_bhp
                .cast_lossy(snarkvm::prelude::LiteralType::Field)
                .map_err(|e| anyhow!("Failed cast_lossy conversion: {}", e))?;
            
            // Convert the hash to a string representation
            casted_to_field.to_string()
        }
    };
    
    // Return the generated hash
    Ok(hash)
}