Version fonctionnelle

Signed-off-by: Yohann D'ANELLO <ynerant@crans.org>

pscheck/base45.py

@@ -0,0 +1,61 @@
+"""
+BSD 2-Clause License
+
+Copyright (c) 2021, Kirei AB
+All rights reserved.
+"""
+
+
+from typing import Union
+
+
+BASE45_CHARSET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:"
+BASE45_DICT = {v: i for i, v in enumerate(BASE45_CHARSET)}
+
+
+def b45encode(buf: bytes) -> bytes:
+    """Convert bytes to base45-encoded string"""
+    res = ""
+    buflen = len(buf)
+    for i in range(0, buflen & ~1, 2):
+        x = (buf[i] << 8) + buf[i + 1]
+        e, x = divmod(x, 45 * 45)
+        d, c = divmod(x, 45)
+        res += BASE45_CHARSET[c] + BASE45_CHARSET[d] + BASE45_CHARSET[e]
+    if buflen & 1:
+        d, c = divmod(buf[-1], 45)
+        res += BASE45_CHARSET[c] + BASE45_CHARSET[d]
+    return res.encode()
+
+
+def b45decode(s: Union[bytes, str]) -> bytes:
+    """Decode base45-encoded string to bytes"""
+    try:
+        if isinstance(s, str):
+            buf = [BASE45_DICT[c] for c in s.strip()]
+        elif isinstance(s, bytes):
+            buf = [BASE45_DICT[c] for c in s.decode()]
+        else:
+            raise TypeError("Type must be 'str' or 'bytes'")
+
+        buflen = len(buf)
+        if buflen % 3 == 1:
+            raise ValueError("Invalid base45 string")
+
+        res = []
+        for i in range(0, buflen, 3):
+            if buflen - i >= 3:
+                x = buf[i] + buf[i + 1] * 45 + buf[i + 2] * 45 * 45
+                if x > 0xFFFF:
+                    raise ValueError
+                res.extend(divmod(x, 256))
+            else:
+                x = buf[i] + buf[i + 1] * 45
+                if x > 0xFF:
+                    raise ValueError
+                res.append(x)
+        return bytes(res)
+    except (ValueError, KeyError, AttributeError):
+        raise ValueError("Invalid base45 string")
+
+