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Hash Chain

VeriFactu · Hash Chain

Hash Chain Deep Dive

Section titled “Hash Chain Deep Dive”

The VeriFactu hash chain ensures data integrity and chronological ordering.

SHA-256 Algorithm

Section titled “SHA-256 Algorithm”

VeriFactu uses SHA-256 (Secure Hash Algorithm 256-bit):

Input: Invoice data + Previous hash
Output: 64-character hex string

Chain Construction

Section titled “Chain Construction”

First Record

Section titled “First Record”
Huella = SHA256(
  NIF_Obligado + "|" +
  Num_Serie + "|" +
  Fecha_Hora + "|" +
  Importe_Total
)

Subsequent Records

Section titled “Subsequent Records”
Huella = SHA256(
  NIF_Obligado + "|" +
  Num_Serie + "|" +
  Fecha_Hora + "|" +
  Importe_Total + "|" +
  Huella_Anterior
)

Chain Validation

Section titled “Chain Validation”

To validate a chain:

  1. Recompute each hash
  2. Verify against stored Huella
  3. Confirm previous hash references

Kreyo Implementation

Section titled “Kreyo Implementation”

Kreyo automatically:

  • Maintains your chain state
  • Computes hashes correctly
  • Handles chain breaks (rare edge cases)
  • Validates before submission