A method of authenticating an identity document implemented by a server and client device that are connected thereto; the client device having first encoded data and an image acquired of said identity document representing at least a photograph of an individual and an optically readable data that are visible on said identity document, and the server having a hash value of a first concatenation of said optically readable data of said identity document and of a first random data, called first hash value; the method comprising the implementation of steps of: (b) Extraction, by the data processing means of the client device, by analysis of said image acquired from said identity document, of: ∘ candidate information representative of the appearance of said photograph as represented in the acquired image; ∘ said optically readable data as represented in the acquired image; (c) Calculation by the data processing means of the client device of: ∘ a first decoded data by application of a decoding process to said candidate information representative of the appearance of said photograph and to the first encoded data, such that said first decoded data corresponds to the first random data if said candidate information representative of the appearance of said photograph matches a reference information representative of the appearance of said photograph; ∘ a hash value of a first concatenation of the extracted optically readable data and of the first decoded data; (d) generation by the data processing means of the client device of a zero-knowledge proof of the calculation of said hash value from the first concatenation of the extracted optically readable data and of the first decoded data; (e) transmission to the server of said zero-knowledge proof of the calculated hash value; (f) verification by the data processing means of the server that: ∘ the zero-knowledge proof is valid, and ∘ the received hash value matches said first hash value possessed by the server. (b) Extraction, by the data processing means of the client device, by analysis of said image acquired from said identity document, of: ∘ candidate information representative of the appearance of said photograph as represented in the acquired image; ∘ said optically readable data as represented in the acquired image; ∘ candidate information representative of the appearance of said photograph as represented in the acquired image; ∘ said optically readable data as represented in the acquired image; (c) Calculation by the data processing means of the client device of: ∘ a first decoded data by application of a decoding process to said candidate information representative of the appearance of said photograph and to the first encoded data, such that said first decoded data corresponds to the first random data if said candidate information representative of the appearance of said photograph matches a reference information representative of the appearance of said photograph; ∘ a hash value of a first concatenation of the extracted optically readable data and of the first decoded data; ∘ a first decoded data by application of a decoding process to said candidate information representative of the appearance of said photograph and to the first encoded data, such that said first decoded data corresponds to the first random data if said candidate information representative of the appearance of said photograph matches a reference information representative of the appearance of said photograph; ∘ a hash value of a first concatenation of the extracted optically readable data and of the first decoded data; (d) generation by the data processing means of the client device of a zero-knowledge proof of the calculation of said hash value from the first concatenation of the extracted optically readable data and of the first decoded data; (e) transmission to the server of said zero-knowledge proof of the calculated hash value; (f) verification by the data processing means of the server that: ∘ the zero-knowledge proof is valid, and ∘ the received hash value matches said first hash value possessed by the server. ∘ the zero-knowledge proof is valid, and ∘ the received hash value matches said first hash value possessed by the server.