elastic/elasticsearch · error · IOException

Invalid DER: stream too short, missing value. Could only rea

Error message

Invalid DER: stream too short, missing value. Could only read {} out of {} bytes

What it means

Thrown by DerParser.readAsn1Object() after allocating a value byte[] of the declared length but reading fewer bytes than requested from derInputStream. The declared length was plausible but the underlying stream ran out of bytes before the value was satisfied.

Source

Thrown at libs/ssl-config/src/main/java/org/elasticsearch/common/ssl/DerParser.java:97

    }

    public Asn1Object readAsn1Object() throws IOException {
        int tag = derInputStream.read();
        if (tag == -1) {
            throw new IOException("Invalid DER: stream too short, missing tag");
        }
        int length = getLength();
        // getLength() can return any 32 bit integer, so ensure that a corrupted encoding won't
        // force us into allocating a very large array
        if (length > maxAsnObjectLength) {
            throw new IOException(
                "Invalid DER: size of ASN.1 object to be parsed appears to be larger than the size of the key file " + "itself."
            );
        }
        byte[] value = new byte[length];
        int n = derInputStream.read(value);
        if (n < length) {
            throw new IOException(
                "Invalid DER: stream too short, missing value. " + "Could only read " + n + " out of " + length + " bytes"
            );
        }
        return new Asn1Object(tag, length, value);

    }

    /**
     * Decode the length of the field. Can only support length
     * encoding up to 4 octets.
     * <p>
     *          In BER/DER encoding, length can be encoded in 2 forms:
     * </p>
     * <ul>
     * <li>Short form. One octet. Bit 8 has value "0" and bits 7-1
     * give the length.
     * </li>
     * <li>Long form. Two to 127 octets (only 4 is supported here).

View on GitHub (pinned to db6a809a66)

Solutions

Confirm the key file is complete: compare its size against a known-good copy, or re-download/re-export.
Validate the PEM base64 round-trips: `openssl pkey -in key.pem -noout -check` should exit 0.
If slicing a DER buffer programmatically, verify the slice length matches the declared outer SEQUENCE length before sub-parsing.
Regenerate the key with a fresh `openssl genpkey`/`openssl pkcs8` if integrity is doubtful.

Example fix

// before: sub-parsing a buffer that was cut short
byte[] truncated = Arrays.copyOf(fullDer, fullDer.length - 10);
new DerParser(truncated).readAsn1Object();

// after: pass the complete buffer
new DerParser(fullDer).readAsn1Object();

Defensive patterns

Strategy: validation

Validate before calling

private static void requireCompleteDer(byte[] der) {
    if (der == null || der.length == 0) throw new IllegalArgumentException("empty DER");
    int idx = 1;
    int lenByte = der[idx++] & 0xFF;
    int declared;
    if ((lenByte & 0x80) == 0) {
        declared = lenByte;
    } else {
        int num = lenByte & 0x7F;
        if (idx + num > der.length) throw new IllegalArgumentException("truncated length field");
        declared = 0;
        for (int i = 0; i < num; i++) declared = (declared << 8) | (der[idx + i] & 0xFF);
    }
    if (1 + (declared > 127 ? 1 + (der[1] & 0x7F) : 1) + declared > der.length) {
        throw new IllegalArgumentException("declared length " + declared + " exceeds available bytes");
    }
}

Prevention

Verify the file size matches the declared outer SEQUENCE length before parsing.
Re-download or re-export keys whose length is suspicious.
Use checksums (sha256) to confirm file integrity after transfer.

When it happens

Trigger: readAsn1Object() reads a tag, getLength() returns N (N <= maxAsnObjectLength), then InputStream.read(value) returns n < N. Happens on DER blobs whose length octet claims more content than is present — typical of a partial file or a byte array that was sliced incorrectly before being handed to DerParser.

Common situations: Key file truncated mid-write (e.g. disk full, scp interrupted), a copy/paste that dropped trailing base64 chars, an off-by-one slice on a DER buffer, or a key that has trailing junk bytes that confuse the length decode of an inner element.

Related errors

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/aa7369f97982aceb. Report an issue: GitHub.