C ABI reference

The native library evb_e2ee_ffi (built from bindings/dart/rust of everabyte/crypto-sdk) exposes the whole protocol through a C ABI. The canonical header is include/evb_e2ee.h in the repository — copy it and include it from your FFI declaration of choice.

Conventions

Return: 0 = OK; negative = error (-1 bad argument, -2 crypto failure, -3 malformed payload, -4 buffer too small, -5 JSON failure, -6 invalid UTF-8, -7 internal lock).
Buffers: caller-allocated; string outputs are NUL-terminated; byte outputs write the length to out_len.
Errors: a short, secret-free message via evb_last_error(buf, cap) — call with cap = 0 first to get the required capacity. evb_clear_last_error() resets the slot.
UMK material crosses the boundary as 96 bytes: X25519 secret (32) ‖ ML-KEM-768 seed (64).

Functions

Randomness

Symbol	Signature	Notes
`evb_random`	`(len u64, out u8, out_cap u64, out_len u64) → i32`	OS CSPRNG fill — use it for salts, nonces, DEKs

Account key (UMK)

Symbol	Signature	Notes
`evb_generate_umk`	`(out u8, out_cap u64, out_len u64) → i32`	96 bytes: sk(32) ‖ seed(64)
`evb_umk_public_keys`	`(sk u8, seed u8, out_json *char, out_cap u64) → i32`	JSON `{publicKeyX25519: b64(32), publicKeyMlkem: b64(1184)}`
`evb_wrap_umk_with_mnemonic`	`(sk, seed, mnemonic char, salt u8(16), nonce u8(12), out_blob char, out_cap) → i32`	Argon2id v3 blob, cap ≥ 8192 recommended
`evb_unwrap_umk_with_mnemonic`	`(blob_b64 char, mnemonic char, out *u8, out_cap 96, out_len) → i32`	candidate chain: v3 → RFC 9106 profile → legacy PBKDF2
`evb_wrap_umk_with_device_key`	`(sk, seed, device_secret u8(32), nonce u8(12), out_blob, out_cap) → i32`	device secret stays on-device
`evb_unwrap_umk_with_device_key`	`(blob_b64, device_secret *u8(32), out, out_cap 96, out_len) → i32`	—

File key (DEK) envelopes

Symbol	Signature	Notes
`evb_wrap_dek_to_umk`	`(dek u8(32), pk_x25519 u8(32), pk_mlkem u8(1184), out_json char, out_cap ≥ 4096) → i32`	HPKE v2 envelope JSON
`evb_unwrap_dek_from_umk`	`(envelope_json char, sk, seed, out u8(32), out_cap, out_len) → i32`	dispatches v2/v1

File content (EVB1)

Symbol	Signature	Notes
`evb1_seal_all`	`(dek u8(32), file_nonce u8(12), plaintext u8, len u64, out u8, out_cap, out_len) → i32`	EVB1 payload = 16 B header + chunks
`evb1_open_all`	`(dek, payload u8, payload_len u64, out u8, out_cap, out_len) → i32`	output capacity ≥ payload − 16

File names

Symbol	Signature	Notes
`evb_derive_wire_alias`	`(sk, seed, real_name char, out char, out_cap 128) → i32`	`"evb-"` + hex64
`evb_encrypt_file_name`	`(dek, real_name char, nonce u8(12), out_blob *char, out_cap 512) → i32`	b64(nonce ‖ ct ‖ tag)
`evb_decrypt_file_name`	`(dek, blob_b64 char, out u8, out_cap, out_len) → i32`	out = UTF-8 name bytes

Primitives & diagnostics

Symbol	Signature	Notes
`evb_hkdf_sha256`	`(ikm, ikm_len, info, info_len, out[32]) → i32`	salt-less HKDF-SHA256
`evb_last_error`	`(buf *char, cap u64) → i32`	`0` written; `> 0` = required capacity
`evb_clear_last_error`	`() → i32`	zeroizes the slot

Buffer sizing cheat-sheet

Output	Recommended capacity
UMK	96
public-keys JSON	2048
mnemonic / device wrap blob	8192
envelope JSON	4096
wire alias	128
encrypted-name blob	512
EVB1 ciphertext	`plaintextLen + 65536 + 16`
decrypted name	real name length + 1

Status codes

Code	Meaning
`0`	OK
`-1`	Bad argument (null / wrong size)
`-2`	Crypto failure (wrong key, RNG)
`-3`	Malformed payload / unsupported version
`-4`	Output buffer too small
`-5`	JSON serialization failure
`-6`	Input not valid UTF-8
`-7`	Internal error-slot lock failure

Getting Started

Core Concepts

Authentication & Security

Storage Guides

Error Handling

Security & Data Protection

Zero-Knowledge SDK

Enterprise & Partners

Resources