diff --git a/verifier24/README b/verifier24/README
new file mode 100644
index 0000000..44d9422
--- /dev/null
+++ b/verifier24/README
@@ -0,0 +1,2 @@
+This is older code from Android 5.1 Marshmallow (SDK ver 24) and older
+that still used mincrypt instead of libcrypto.
diff --git a/verifier24/verifier.cpp b/verifier24/verifier.cpp
new file mode 100644
index 0000000..98c7337
--- /dev/null
+++ b/verifier24/verifier.cpp
@@ -0,0 +1,471 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "asn1_decoder.h"
+#include "common.h"
+#include "ui.h"
+#include "verifier.h"
+
+#include "mincrypt/dsa_sig.h"
+#include "mincrypt/p256.h"
+#include "mincrypt/p256_ecdsa.h"
+#include "mincrypt/rsa.h"
+#include "mincrypt/sha.h"
+#include "mincrypt/sha256.h"
+
+#include <errno.h>
+#include <malloc.h>
+#include <stdio.h>
+#include <string.h>
+
+//extern RecoveryUI* ui;
+
+#define PUBLIC_KEYS_FILE "/res/keys"
+
+/*
+ * Simple version of PKCS#7 SignedData extraction. This extracts the
+ * signature OCTET STRING to be used for signature verification.
+ *
+ * For full details, see http://www.ietf.org/rfc/rfc3852.txt
+ *
+ * The PKCS#7 structure looks like:
+ *
+ *   SEQUENCE (ContentInfo)
+ *     OID (ContentType)
+ *     [0] (content)
+ *       SEQUENCE (SignedData)
+ *         INTEGER (version CMSVersion)
+ *         SET (DigestAlgorithmIdentifiers)
+ *         SEQUENCE (EncapsulatedContentInfo)
+ *         [0] (CertificateSet OPTIONAL)
+ *         [1] (RevocationInfoChoices OPTIONAL)
+ *         SET (SignerInfos)
+ *           SEQUENCE (SignerInfo)
+ *             INTEGER (CMSVersion)
+ *             SEQUENCE (SignerIdentifier)
+ *             SEQUENCE (DigestAlgorithmIdentifier)
+ *             SEQUENCE (SignatureAlgorithmIdentifier)
+ *             OCTET STRING (SignatureValue)
+ */
+static bool read_pkcs7(uint8_t* pkcs7_der, size_t pkcs7_der_len, uint8_t** sig_der,
+        size_t* sig_der_length) {
+    asn1_context_t* ctx = asn1_context_new(pkcs7_der, pkcs7_der_len);
+    if (ctx == NULL) {
+        return false;
+    }
+
+    asn1_context_t* pkcs7_seq = asn1_sequence_get(ctx);
+    if (pkcs7_seq != NULL && asn1_sequence_next(pkcs7_seq)) {
+        asn1_context_t *signed_data_app = asn1_constructed_get(pkcs7_seq);
+        if (signed_data_app != NULL) {
+            asn1_context_t* signed_data_seq = asn1_sequence_get(signed_data_app);
+            if (signed_data_seq != NULL
+                    && asn1_sequence_next(signed_data_seq)
+                    && asn1_sequence_next(signed_data_seq)
+                    && asn1_sequence_next(signed_data_seq)
+                    && asn1_constructed_skip_all(signed_data_seq)) {
+                asn1_context_t *sig_set = asn1_set_get(signed_data_seq);
+                if (sig_set != NULL) {
+                    asn1_context_t* sig_seq = asn1_sequence_get(sig_set);
+                    if (sig_seq != NULL
+                            && asn1_sequence_next(sig_seq)
+                            && asn1_sequence_next(sig_seq)
+                            && asn1_sequence_next(sig_seq)
+                            && asn1_sequence_next(sig_seq)) {
+                        uint8_t* sig_der_ptr;
+                        if (asn1_octet_string_get(sig_seq, &sig_der_ptr, sig_der_length)) {
+                            *sig_der = (uint8_t*) malloc(*sig_der_length);
+                            if (*sig_der != NULL) {
+                                memcpy(*sig_der, sig_der_ptr, *sig_der_length);
+                            }
+                        }
+                        asn1_context_free(sig_seq);
+                    }
+                    asn1_context_free(sig_set);
+                }
+                asn1_context_free(signed_data_seq);
+            }
+            asn1_context_free(signed_data_app);
+        }
+        asn1_context_free(pkcs7_seq);
+    }
+    asn1_context_free(ctx);
+
+    return *sig_der != NULL;
+}
+
+// Look for an RSA signature embedded in the .ZIP file comment given
+// the path to the zip.  Verify it matches one of the given public
+// keys.
+//
+// Return VERIFY_SUCCESS, VERIFY_FAILURE (if any error is encountered
+// or no key matches the signature).
+int verify_file(unsigned char* addr, size_t length) {
+    //ui->SetProgress(0.0);
+
+    int numKeys;
+    Certificate* pKeys = load_keys(PUBLIC_KEYS_FILE, &numKeys);
+    if (pKeys == NULL) {
+        LOGE("Failed to load keys\n");
+        return INSTALL_CORRUPT;
+    }
+    LOGI("%d key(s) loaded from %s\n", numKeys, PUBLIC_KEYS_FILE);
+
+    // An archive with a whole-file signature will end in six bytes:
+    //
+    //   (2-byte signature start) $ff $ff (2-byte comment size)
+    //
+    // (As far as the ZIP format is concerned, these are part of the
+    // archive comment.)  We start by reading this footer, this tells
+    // us how far back from the end we have to start reading to find
+    // the whole comment.
+
+#define FOOTER_SIZE 6
+
+    if (length < FOOTER_SIZE) {
+        LOGE("not big enough to contain footer\n");
+        return VERIFY_FAILURE;
+    }
+
+    unsigned char* footer = addr + length - FOOTER_SIZE;
+
+    if (footer[2] != 0xff || footer[3] != 0xff) {
+        LOGE("footer is wrong\n");
+        return VERIFY_FAILURE;
+    }
+
+    size_t comment_size = footer[4] + (footer[5] << 8);
+    size_t signature_start = footer[0] + (footer[1] << 8);
+    LOGI("comment is %zu bytes; signature %zu bytes from end\n",
+         comment_size, signature_start);
+
+    if (signature_start <= FOOTER_SIZE) {
+        LOGE("Signature start is in the footer");
+        return VERIFY_FAILURE;
+    }
+
+#define EOCD_HEADER_SIZE 22
+
+    // The end-of-central-directory record is 22 bytes plus any
+    // comment length.
+    size_t eocd_size = comment_size + EOCD_HEADER_SIZE;
+
+    if (length < eocd_size) {
+        LOGE("not big enough to contain EOCD\n");
+        return VERIFY_FAILURE;
+    }
+
+    // Determine how much of the file is covered by the signature.
+    // This is everything except the signature data and length, which
+    // includes all of the EOCD except for the comment length field (2
+    // bytes) and the comment data.
+    size_t signed_len = length - eocd_size + EOCD_HEADER_SIZE - 2;
+
+    unsigned char* eocd = addr + length - eocd_size;
+
+    // If this is really is the EOCD record, it will begin with the
+    // magic number $50 $4b $05 $06.
+    if (eocd[0] != 0x50 || eocd[1] != 0x4b ||
+        eocd[2] != 0x05 || eocd[3] != 0x06) {
+        LOGE("signature length doesn't match EOCD marker\n");
+        return VERIFY_FAILURE;
+    }
+
+    size_t i;
+    for (i = 4; i < eocd_size-3; ++i) {
+        if (eocd[i  ] == 0x50 && eocd[i+1] == 0x4b &&
+            eocd[i+2] == 0x05 && eocd[i+3] == 0x06) {
+            // if the sequence $50 $4b $05 $06 appears anywhere after
+            // the real one, minzip will find the later (wrong) one,
+            // which could be exploitable.  Fail verification if
+            // this sequence occurs anywhere after the real one.
+            LOGE("EOCD marker occurs after start of EOCD\n");
+            return VERIFY_FAILURE;
+        }
+    }
+
+#define BUFFER_SIZE 4096
+
+    bool need_sha1 = false;
+    bool need_sha256 = false;
+    for (i = 0; i < numKeys; ++i) {
+        switch (pKeys[i].hash_len) {
+            case SHA_DIGEST_SIZE: need_sha1 = true; break;
+            case SHA256_DIGEST_SIZE: need_sha256 = true; break;
+        }
+    }
+
+    SHA_CTX sha1_ctx;
+    SHA256_CTX sha256_ctx;
+    SHA_init(&sha1_ctx);
+    SHA256_init(&sha256_ctx);
+
+    double frac = -1.0;
+    size_t so_far = 0;
+    while (so_far < signed_len) {
+        size_t size = signed_len - so_far;
+        if (size > BUFFER_SIZE) size = BUFFER_SIZE;
+
+        if (need_sha1) SHA_update(&sha1_ctx, addr + so_far, size);
+        if (need_sha256) SHA256_update(&sha256_ctx, addr + so_far, size);
+        so_far += size;
+
+        double f = so_far / (double)signed_len;
+        if (f > frac + 0.02 || size == so_far) {
+            //ui->SetProgress(f);
+            frac = f;
+        }
+    }
+
+    const uint8_t* sha1 = SHA_final(&sha1_ctx);
+    const uint8_t* sha256 = SHA256_final(&sha256_ctx);
+
+    uint8_t* sig_der = NULL;
+    size_t sig_der_length = 0;
+
+    size_t signature_size = signature_start - FOOTER_SIZE;
+    if (!read_pkcs7(eocd + eocd_size - signature_start, signature_size, &sig_der,
+            &sig_der_length)) {
+        LOGE("Could not find signature DER block\n");
+        return VERIFY_FAILURE;
+    }
+
+    /*
+     * Check to make sure at least one of the keys matches the signature. Since
+     * any key can match, we need to try each before determining a verification
+     * failure has happened.
+     */
+    for (i = 0; i < numKeys; ++i) {
+        const uint8_t* hash;
+        switch (pKeys[i].hash_len) {
+            case SHA_DIGEST_SIZE: hash = sha1; break;
+            case SHA256_DIGEST_SIZE: hash = sha256; break;
+            default: continue;
+        }
+
+        // The 6 bytes is the "(signature_start) $ff $ff (comment_size)" that
+        // the signing tool appends after the signature itself.
+        if (pKeys[i].key_type == Certificate::RSA) {
+            if (sig_der_length < RSANUMBYTES) {
+                // "signature" block isn't big enough to contain an RSA block.
+                LOGI("signature is too short for RSA key %zu\n", i);
+                continue;
+            }
+
+            if (!RSA_verify(pKeys[i].rsa, sig_der, RSANUMBYTES,
+                            hash, pKeys[i].hash_len)) {
+                LOGI("failed to verify against RSA key %zu\n", i);
+                continue;
+            }
+
+            LOGI("whole-file signature verified against RSA key %zu\n", i);
+            free(sig_der);
+            return VERIFY_SUCCESS;
+        } else if (pKeys[i].key_type == Certificate::EC
+                && pKeys[i].hash_len == SHA256_DIGEST_SIZE) {
+            p256_int r, s;
+            if (!dsa_sig_unpack(sig_der, sig_der_length, &r, &s)) {
+                LOGI("Not a DSA signature block for EC key %zu\n", i);
+                continue;
+            }
+
+            p256_int p256_hash;
+            p256_from_bin(hash, &p256_hash);
+            if (!p256_ecdsa_verify(&(pKeys[i].ec->x), &(pKeys[i].ec->y),
+                                   &p256_hash, &r, &s)) {
+                LOGI("failed to verify against EC key %zu\n", i);
+                continue;
+            }
+
+            LOGI("whole-file signature verified against EC key %zu\n", i);
+            free(sig_der);
+            return VERIFY_SUCCESS;
+        } else {
+            LOGI("Unknown key type %d\n", pKeys[i].key_type);
+        }
+		LOGI("i: %i, eocd_size: %i, RSANUMBYTES: %i\n", i, eocd_size, RSANUMBYTES);
+    }
+    free(sig_der);
+    LOGE("failed to verify whole-file signature\n");
+    return VERIFY_FAILURE;
+}
+
+// Reads a file containing one or more public keys as produced by
+// DumpPublicKey:  this is an RSAPublicKey struct as it would appear
+// as a C source literal, eg:
+//
+//  "{64,0xc926ad21,{1795090719,...,-695002876},{-857949815,...,1175080310}}"
+//
+// For key versions newer than the original 2048-bit e=3 keys
+// supported by Android, the string is preceded by a version
+// identifier, eg:
+//
+//  "v2 {64,0xc926ad21,{1795090719,...,-695002876},{-857949815,...,1175080310}}"
+//
+// (Note that the braces and commas in this example are actual
+// characters the parser expects to find in the file; the ellipses
+// indicate more numbers omitted from this example.)
+//
+// The file may contain multiple keys in this format, separated by
+// commas.  The last key must not be followed by a comma.
+//
+// A Certificate is a pair of an RSAPublicKey and a particular hash
+// (we support SHA-1 and SHA-256; we store the hash length to signify
+// which is being used).  The hash used is implied by the version number.
+//
+//       1: 2048-bit RSA key with e=3 and SHA-1 hash
+//       2: 2048-bit RSA key with e=65537 and SHA-1 hash
+//       3: 2048-bit RSA key with e=3 and SHA-256 hash
+//       4: 2048-bit RSA key with e=65537 and SHA-256 hash
+//       5: 256-bit EC key using the NIST P-256 curve parameters and SHA-256 hash
+//
+// Returns NULL if the file failed to parse, or if it contain zero keys.
+Certificate*
+load_keys(const char* filename, int* numKeys) {
+    Certificate* out = NULL;
+    *numKeys = 0;
+
+    FILE* f = fopen(filename, "r");
+    if (f == NULL) {
+        LOGE("opening %s: %s\n", filename, strerror(errno));
+        goto exit;
+    }
+
+    {
+        int i;
+        bool done = false;
+        while (!done) {
+            ++*numKeys;
+            out = (Certificate*)realloc(out, *numKeys * sizeof(Certificate));
+            Certificate* cert = out + (*numKeys - 1);
+            memset(cert, '\0', sizeof(Certificate));
+
+            char start_char;
+            if (fscanf(f, " %c", &start_char) != 1) goto exit;
+            if (start_char == '{') {
+                // a version 1 key has no version specifier.
+                cert->key_type = Certificate::RSA;
+                cert->rsa = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+                cert->rsa->exponent = 3;
+                cert->hash_len = SHA_DIGEST_SIZE;
+            } else if (start_char == 'v') {
+                int version;
+                if (fscanf(f, "%d {", &version) != 1) goto exit;
+                switch (version) {
+                    case 2:
+                        cert->key_type = Certificate::RSA;
+                        cert->rsa = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+                        cert->rsa->exponent = 65537;
+                        cert->hash_len = SHA_DIGEST_SIZE;
+                        break;
+                    case 3:
+                        cert->key_type = Certificate::RSA;
+                        cert->rsa = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+                        cert->rsa->exponent = 3;
+                        cert->hash_len = SHA256_DIGEST_SIZE;
+                        break;
+                    case 4:
+                        cert->key_type = Certificate::RSA;
+                        cert->rsa = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+                        cert->rsa->exponent = 65537;
+                        cert->hash_len = SHA256_DIGEST_SIZE;
+                        break;
+                    case 5:
+                        cert->key_type = Certificate::EC;
+                        cert->ec = (ECPublicKey*)calloc(1, sizeof(ECPublicKey));
+                        cert->hash_len = SHA256_DIGEST_SIZE;
+                        break;
+                    default:
+                        goto exit;
+                }
+            }
+
+            if (cert->key_type == Certificate::RSA) {
+                RSAPublicKey* key = cert->rsa;
+                if (fscanf(f, " %i , 0x%x , { %u",
+                           &(key->len), &(key->n0inv), &(key->n[0])) != 3) {
+                    goto exit;
+                }
+                if (key->len != RSANUMWORDS) {
+                    LOGE("key length (%d) does not match expected size\n", key->len);
+                    goto exit;
+                }
+                for (i = 1; i < key->len; ++i) {
+                    if (fscanf(f, " , %u", &(key->n[i])) != 1) goto exit;
+                }
+                if (fscanf(f, " } , { %u", &(key->rr[0])) != 1) goto exit;
+                for (i = 1; i < key->len; ++i) {
+                    if (fscanf(f, " , %u", &(key->rr[i])) != 1) goto exit;
+                }
+                fscanf(f, " } } ");
+
+                LOGI("read key e=%d hash=%d\n", key->exponent, cert->hash_len);
+            } else if (cert->key_type == Certificate::EC) {
+                ECPublicKey* key = cert->ec;
+                int key_len;
+                unsigned int byte;
+                uint8_t x_bytes[P256_NBYTES];
+                uint8_t y_bytes[P256_NBYTES];
+                if (fscanf(f, " %i , { %u", &key_len, &byte) != 2) goto exit;
+                if (key_len != P256_NBYTES) {
+                    LOGE("Key length (%d) does not match expected size %d\n", key_len, P256_NBYTES);
+                    goto exit;
+                }
+                x_bytes[P256_NBYTES - 1] = byte;
+                for (i = P256_NBYTES - 2; i >= 0; --i) {
+                    if (fscanf(f, " , %u", &byte) != 1) goto exit;
+                    x_bytes[i] = byte;
+                }
+                if (fscanf(f, " } , { %u", &byte) != 1) goto exit;
+                y_bytes[P256_NBYTES - 1] = byte;
+                for (i = P256_NBYTES - 2; i >= 0; --i) {
+                    if (fscanf(f, " , %u", &byte) != 1) goto exit;
+                    y_bytes[i] = byte;
+                }
+                fscanf(f, " } } ");
+                p256_from_bin(x_bytes, &key->x);
+                p256_from_bin(y_bytes, &key->y);
+            } else {
+                LOGE("Unknown key type %d\n", cert->key_type);
+                goto exit;
+            }
+
+            // if the line ends in a comma, this file has more keys.
+            switch (fgetc(f)) {
+            case ',':
+                // more keys to come.
+                break;
+
+            case EOF:
+                done = true;
+                break;
+
+            default:
+                LOGE("unexpected character between keys\n");
+                goto exit;
+            }
+        }
+    }
+
+    fclose(f);
+    return out;
+
+exit:
+    if (f) fclose(f);
+    free(out);
+    *numKeys = 0;
+    return NULL;
+}
diff --git a/verifier24/verifier.h b/verifier24/verifier.h
new file mode 100644
index 0000000..17ab257
--- /dev/null
+++ b/verifier24/verifier.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _RECOVERY_VERIFIER_H
+#define _RECOVERY_VERIFIER_H
+
+#include "mincrypt/p256.h"
+#include "mincrypt/rsa.h"
+
+#define ASSUMED_UPDATE_BINARY_NAME  "META-INF/com/google/android/update-binary"
+
+enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT };
+
+static const float VERIFICATION_PROGRESS_FRACTION = 0.25;
+
+typedef struct {
+    p256_int x;
+    p256_int y;
+} ECPublicKey;
+
+typedef struct {
+    typedef enum {
+        RSA,
+        EC,
+    } KeyType;
+
+    int hash_len;  // SHA_DIGEST_SIZE (SHA-1) or SHA256_DIGEST_SIZE (SHA-256)
+    KeyType key_type;
+    RSAPublicKey* rsa;
+    ECPublicKey* ec;
+} Certificate;
+
+/* addr and length define a an update package file that has been
+ * loaded (or mmap'ed, or whatever) into memory.  Verify that the file
+ * is signed and the signature matches one of the given keys.  Return
+ * one of the constants below.
+ */
+int verify_file(unsigned char* addr, size_t length);
+
+Certificate* load_keys(const char* filename, int* numKeys);
+
+#define VERIFY_SUCCESS        0
+#define VERIFY_FAILURE        1
+
+#endif  /* _RECOVERY_VERIFIER_H */