diff --git a/boot/zephyr/single_loader.c b/boot/zephyr/single_loader.c
index af2d398..f6c65f6 100644
--- a/boot/zephyr/single_loader.c
+++ b/boot/zephyr/single_loader.c
@@ -19,7 +19,7 @@
 static const struct flash_area *_fa_p;
 static struct image_header _hdr = { 0 };
 
-#ifdef MCUBOOT_VALIDATE_PRIMARY_SLOT
+#if defined(MCUBOOT_VALIDATE_PRIMARY_SLOT) || defined(MCUBOOT_VALIDATE_PRIMARY_SLOT_ONCE)
 /**
  * Validate hash of a primary boot image.
  *
@@ -28,7 +28,7 @@
  *
  * @return		FIH_SUCCESS on success, error code otherwise
  */
-inline static fih_int
+fih_int
 boot_image_validate(const struct flash_area *fa_p,
                     struct image_header *hdr)
 {
@@ -41,14 +41,54 @@
      * the pointer from compilation.
      */
     /* Validate hash */
+    if (IS_ENCRYPTED(hdr))
+    {
+        /* Clear the encrypted flag we didn't supply a key
+         * This flag could be set if there was a decryption in place
+         * was performed. We will try to validate the image, and if still
+         * encrypted the validation will fail, and go in panic mode
+         */
+        hdr->ih_flags &= ~(ENCRYPTIONFLAGS);
+    }
     FIH_CALL(bootutil_img_validate, fih_rc, NULL, 0, hdr, fa_p, tmpbuf,
              BOOT_TMPBUF_SZ, NULL, 0, NULL);
 
     FIH_RET(fih_rc);
 }
-#endif /* MCUBOOT_VALIDATE_PRIMARY_SLOT */
+#endif /* MCUBOOT_VALIDATE_PRIMARY_SLOT || MCUBOOT_VALIDATE_PRIMARY_SLOT_ONCE*/
 
 
+inline static fih_int
+boot_image_validate_once(const struct flash_area *fa_p,
+                    struct image_header *hdr)
+{
+    static struct boot_swap_state state;
+    int rc;
+    fih_int fih_rc = FIH_FAILURE;
+
+    memset(&state, 0, sizeof(struct boot_swap_state));
+    rc = boot_read_swap_state(fa_p, &state);
+    if (rc != 0)
+        FIH_RET(FIH_FAILURE);
+    if (state.magic != BOOT_MAGIC_GOOD
+            || state.image_ok != BOOT_FLAG_SET) {
+        /* At least validate the image once */
+        FIH_CALL(boot_image_validate, fih_rc, fa_p, hdr);
+        if (fih_not_eq(fih_rc, FIH_SUCCESS)) {
+            FIH_RET(FIH_FAILURE);
+        }
+        if (state.magic != BOOT_MAGIC_GOOD) {
+            rc = boot_write_magic(fa_p);
+            if (rc != 0)
+                FIH_RET(FIH_FAILURE);
+        }
+        rc = boot_write_image_ok(fa_p);
+        if (rc != 0)
+            FIH_RET(FIH_FAILURE);
+    }
+    FIH_RET(FIH_SUCCESS);
+}
+
 /**
  * Attempts to load image header from flash; verifies flash header fields.
  *
@@ -90,6 +130,307 @@
     return 0;
 }
 
+#ifdef MCUBOOT_ENC_IMAGES
+
+/**
+ * Validate hash of a primary boot image doing on the fly decryption as well
+ *
+ * @param[in]	fa_p	flash area pointer
+ * @param[in]	hdr	boot image header pointer
+ *
+ * @return		FIH_SUCCESS on success, error code otherwise
+ */
+inline static fih_int
+boot_image_validate_encrypted(const struct flash_area *fa_p,
+                    struct image_header *hdr)
+{
+    static uint8_t tmpbuf[BOOT_TMPBUF_SZ];
+    fih_int fih_rc = FIH_FAILURE;
+
+    struct boot_loader_state boot_data;
+    struct boot_loader_state *state = &boot_data;
+    struct boot_status _bs;
+    struct boot_status *bs = &_bs;
+    uint8_t image_index;
+    int rc;
+
+    memset(&boot_data, 0, sizeof(struct boot_loader_state));
+    image_index = BOOT_CURR_IMG(state);
+    if (MUST_DECRYPT(fa_p, image_index, hdr)) {
+        rc = boot_enc_load(BOOT_CURR_ENC(state), image_index, hdr, fa_p, bs);
+        if (rc < 0) {
+            FIH_RET(fih_rc);
+        }
+        if (rc == 0 && boot_enc_set_key(BOOT_CURR_ENC(state), 0, bs)) {
+            FIH_RET(fih_rc);
+        }
+    }
+    FIH_CALL(bootutil_img_validate, fih_rc, BOOT_CURR_ENC(state), image_index,
+             hdr, fa_p, tmpbuf, BOOT_TMPBUF_SZ, NULL, 0, NULL);
+
+    FIH_RET(fih_rc);
+}
+
+/*
+ * Compute the total size of the given image.  Includes the size of
+ * the TLVs.
+ */
+static int
+read_image_size(const struct flash_area *fa_p,
+        struct image_header *hdr,
+        uint32_t *size)
+{
+    struct image_tlv_info info;
+    uint32_t off;
+    uint32_t protect_tlv_size;
+    int rc;
+
+    off = BOOT_TLV_OFF(hdr);
+
+    if (flash_area_read(fa_p, off, &info, sizeof(info))) {
+        rc = BOOT_EFLASH;
+        goto done;
+    }
+
+    protect_tlv_size = hdr->ih_protect_tlv_size;
+    if (info.it_magic == IMAGE_TLV_PROT_INFO_MAGIC) {
+        if (protect_tlv_size != info.it_tlv_tot) {
+            rc = BOOT_EBADIMAGE;
+            goto done;
+        }
+
+        if (flash_area_read(fa_p, off + info.it_tlv_tot, &info, sizeof(info))) {
+            rc = BOOT_EFLASH;
+            goto done;
+        }
+    } else if (protect_tlv_size != 0) {
+        rc = BOOT_EBADIMAGE;
+        goto done;
+    }
+
+    if (info.it_magic != IMAGE_TLV_INFO_MAGIC) {
+        rc = BOOT_EBADIMAGE;
+        goto done;
+    }
+
+    *size = off + protect_tlv_size + info.it_tlv_tot;
+    rc = 0;
+
+done:
+    return rc;
+}
+
+
+/* Get the SOC's flash erase block size from the DTS, fallback to 1024. */
+#define SOC_FLASH_ERASE_BLK_SZ \
+         DT_PROP_OR(DT_CHOSEN(zephyr_flash), erase_block_size,1024)
+
+/**
+ * reads, decrypts in RAM & write back the decrypted image in the same region
+ * This function is NOT power failsafe since the image is decrypted in the RAM
+ * buffer.
+ *
+ * @param flash_area            The ID of the source flash area.
+ * @param off_src               The offset within the flash area to
+ *                                  copy from.
+ * @param sz                    The number of bytes to copy. should match erase sector
+ *
+ * @return                      0 on success; nonzero on failure.
+ */
+int
+decrypt_region_inplace(struct boot_loader_state *state,
+                 const struct flash_area *fap,
+                 struct image_header *hdr,
+                 uint32_t off, uint32_t sz)
+{
+    uint32_t bytes_copied;
+    int chunk_sz;
+    int rc;
+    uint32_t tlv_off;
+    size_t blk_off;
+    uint16_t idx;
+    uint32_t blk_sz;
+    uint8_t image_index;
+
+    static uint8_t buf[SOC_FLASH_ERASE_BLK_SZ] __attribute__((aligned));
+    assert(sz <= sizeof buf);
+
+    bytes_copied = 0;
+    while (bytes_copied < sz) {
+        if (sz - bytes_copied > sizeof buf) {
+            chunk_sz = sizeof buf;
+        } else {
+            chunk_sz = sz - bytes_copied;
+        }
+
+        rc = flash_area_read(fap, off + bytes_copied, buf, chunk_sz);
+        if (rc != 0) {
+            return BOOT_EFLASH;
+        }
+
+        image_index = BOOT_CURR_IMG(state);
+        if (IS_ENCRYPTED(hdr)) {
+            blk_sz = chunk_sz;
+            idx = 0;
+            if (off + bytes_copied < hdr->ih_hdr_size) {
+                /* do not decrypt header */
+                if (hdr->ih_hdr_size > (off + bytes_copied + chunk_sz)) {
+                    /* all bytes in header, skip decryption */
+                    blk_sz = 0;
+                }
+                else {
+                    blk_sz = off + bytes_copied + chunk_sz - hdr->ih_hdr_size;
+                }
+
+                blk_off = 0;
+                idx = hdr->ih_hdr_size;
+            } else {
+                blk_off = ((off + bytes_copied) - hdr->ih_hdr_size) & 0xf;
+            }
+            tlv_off = BOOT_TLV_OFF(hdr);
+            if (off + bytes_copied + chunk_sz > tlv_off) {
+                /* do not decrypt TLVs */
+                if (off + bytes_copied >= tlv_off) {
+                    blk_sz = 0;
+                } else {
+                    blk_sz = tlv_off - (off + bytes_copied);
+                }
+            }
+            boot_encrypt(BOOT_CURR_ENC(state), image_index, fap,
+                    (off + bytes_copied + idx) - hdr->ih_hdr_size, blk_sz,
+                    blk_off, &buf[idx]);
+        }
+        rc = flash_area_erase(fap, off + bytes_copied, chunk_sz);
+        if (rc != 0) {
+            return BOOT_EFLASH;
+        }
+        rc = flash_area_write(fap, off + bytes_copied, buf, chunk_sz);
+        if (rc != 0) {
+            return BOOT_EFLASH;
+        }
+
+        bytes_copied += chunk_sz;
+
+        MCUBOOT_WATCHDOG_FEED();
+    }
+
+    return 0;
+}
+
+/**
+ * Check if a image was encrypted into the first slot, and decrypt it
+ * in place. this operation is not power failsafe.
+ *
+ * The operation is done by checking the last flash sector, and using it as a
+ * temporarely scratch partition. The
+ *
+ * @param[in]	fa_p	flash area pointer
+ * @param[in]	hdr	boot image header pointer
+ *
+ * @return		FIH_SUCCESS on success, error code otherwise
+ */
+inline static fih_int
+decrypt_image_inplace(const struct flash_area *fa_p,
+                     struct image_header *hdr)
+{
+    fih_int fih_rc = FIH_FAILURE;
+    int rc;
+    struct boot_loader_state boot_data;
+    struct boot_loader_state *state = &boot_data;
+    struct boot_status _bs;
+    struct boot_status *bs = &_bs;
+    size_t size;
+    size_t sect_size;
+    size_t sect_count;
+    size_t sect;
+    uint8_t image_index;
+    struct flash_sector sector;
+
+    memset(&boot_data, 0, sizeof(struct boot_loader_state));
+    memset(&_bs, 0, sizeof(struct boot_status));
+
+    /* Get size from last sector to know page/sector erase size */
+    rc = flash_area_sector_from_off(boot_status_off(fa_p), &sector);
+
+
+    image_index = BOOT_CURR_IMG(state);
+
+    if (MUST_DECRYPT(fa_p, image_index, hdr)) {
+#if 0 //Skip this step?, the image will just not boot if it's not decrypted properly
+         /* First check if the encrypted image is a good image before decrypting */
+        FIH_CALL(boot_image_validate_encrypted,fih_rc,_fa_p,&_hdr);
+        if (fih_not_eq(fih_rc, FIH_SUCCESS)) {
+             FIH_RET(fih_rc);
+        }
+#endif
+        memset(&boot_data, 0, sizeof(struct boot_loader_state));
+        /* Load the encryption keys into cache */
+        rc = boot_enc_load(BOOT_CURR_ENC(state), image_index, hdr, fa_p, bs);
+        if (rc < 0) {
+            FIH_RET(fih_rc);
+        }
+        if (rc == 0 && boot_enc_set_key(BOOT_CURR_ENC(state), 0, bs)) {
+            FIH_RET(fih_rc);
+        }
+    }
+    else
+    {
+        /* Expected encrypted image! */
+        FIH_RET(fih_rc);
+    }
+
+    uint32_t src_size = 0;
+    rc = read_image_size(fa_p,hdr, &src_size);
+    if (rc != 0) {
+        FIH_RET(fih_rc);
+    }
+
+    sect_size = sector.fs_size;
+    sect_count = fa_p->fa_size / sect_size;
+    for (sect = 0, size = 0; size < src_size && sect < sect_count; sect++) {
+        rc = decrypt_region_inplace(state, fa_p,hdr, size, sect_size);
+        if (rc != 0) {
+            FIH_RET(fih_rc);
+        }
+        size += sect_size;
+    }
+
+    fih_rc = FIH_SUCCESS;
+    FIH_RET(fih_rc);
+}
+
+int
+boot_handle_enc_fw()
+{
+    int rc = -1;
+    fih_int fih_rc = FIH_FAILURE;
+
+    rc = flash_area_open(FLASH_AREA_IMAGE_PRIMARY(0), &_fa_p);
+    assert(rc == 0);
+
+    rc = boot_image_load_header(_fa_p, &_hdr);
+    if (rc != 0) {
+        goto out;
+    }
+
+    if (IS_ENCRYPTED(&_hdr)) {
+        //encrypted, we need to decrypt in place
+        FIH_CALL(decrypt_image_inplace,fih_rc,_fa_p,&_hdr);
+        if (fih_not_eq(fih_rc, FIH_SUCCESS)) {
+            rc = -1;
+            goto out;
+        }
+    }
+    else
+    {
+        rc = 0;
+    }
+
+out:
+    flash_area_close(_fa_p);
+    return rc;
+}
+#endif
 
 /**
  * Gather information on image and prepare for booting.
@@ -116,6 +457,11 @@
     if (fih_not_eq(fih_rc, FIH_SUCCESS)) {
         goto out;
     }
+#elif defined(MCUBOOT_VALIDATE_PRIMARY_SLOT_ONCE)
+    FIH_CALL(boot_image_validate_once, fih_rc, _fa_p, &_hdr);
+    if (fih_not_eq(fih_rc, FIH_SUCCESS)) {
+        goto out;
+    }
 #else
     fih_rc = FIH_SUCCESS;
 #endif /* MCUBOOT_VALIDATE_PRIMARY_SLOT */