ConnectBot SSH Client Library is written in Kotlin with Kaitai Struct and KStateMachine. Prior to 0.3.1, DerReader.readLength() accepts excessive long-form DER length octets, accumulates them into an Int, and primitive readers allocate arrays without checking the declared size against the remaining input. An application or user that loads an attacker-provided private-key file through SshClient.authenticatePublicKey(), SshKeys.decodePemPrivateKey(), SshSigning.sign(), or SshSigning.getPublicKey() can trigger integer wraparound, excessive allocation, or an uncaught OutOfMemoryError. SSH server host keys and agent-forwarding messages do not use this application-supplied private-key input path. No usable weakened key and no confidentiality or integrity impact have been demonstrated. This issue is fixed in version 0.3.1.

Affected: Maven: org.connectbot.sshlib:sshlib

## Summary

The DER parser used for application-supplied private keys did not safely validate encoded length values before converting them to `Int` values or allocating arrays.

A malformed private-key file could encode a length that overflowed or wrapped around, or request an allocation much larger than the available input. This could cause parsing errors or an uncaught `OutOfMemoryError`, potentially terminating the application process.

## Details

The issue was in `DerReader.readLength()` and primitive readers such as `readInteger()`.

`readLength()` previously accepted up to 127 length octets and accumulated them into an `Int`:

```kotlin length = (length shl 8) or nextByte ```

This permitted integer overflow. For example:

- `0x1_0000_0001` wrapped to `1`. - `0x8000_0000` wrapped to `Int.MIN_VALUE`.

Primitive readers then allocated memory based on the resulting value without first checking it against the remaining input:

```kotlin val bytes = ByteArray(length) data.get(bytes) ```

A six-byte DER value declaring a 1 GiB INTEGER caused an immediate `OutOfMemoryError` when tested with a constrained JVM heap. Because `OutOfMemoryError` is not an `Exception`, it is not caught by the public-key authentication error handling and may terminate the application process.

A zero-length DER INTEGER is also invalid, but it does not produce `BigInteger.ZERO`: Java throws `NumberFormatException` when constructing a `BigInteger` from an empty byte array. No weakened or usable crypt…