Function verify_message 

pub fn verify_message<'a>(
    pyth_storage_account: &AccountInfo<'_>,
    instruction_sysvar: &AccountInfo<'_>,
    message_data: &'a [u8],
    ed25519_instruction_index: u16,
    signature_index: u8,
    message_offset: u16,
) -> Result<VerifiedMessage<'a>, SignatureVerificationError>

Verifies a ed25519 signature on Solana by checking that the transaction contains a correct call to the built-in ed25519_program.

• message_data is the signed message that is being verified.
• ed25519_instruction_index is the index of the ed25519_program instruction within the transaction. This instruction must precede the current instruction.
• signature_index is the index of the signature within the inputs to the ed25519_program.
• message_offset is the offset of the signed message within the input data for the current instruction.